JP4195970B2 - Digital still camera - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a digital still camera, and more particularly to a digital still camera having a continuous shooting function.
[0002]
[Prior art]
In recent years, digital still cameras have been widely used, and along with the spread, various functions have been installed in digital still cameras. One of these functions is the continuous shooting function.
[0003]
Here, the continuous shooting function means a function that allows a user to take a plurality of continuous images at regular intervals with a single operation on the digital still camera. This is a convenient function for the user because it never misses a photo opportunity.
[0004]
In the operation by the continuous shooting function, since a plurality of images are acquired within a short time, a large recording capacity of a storage unit such as a semiconductor memory built in the digital still camera is required. However, it can be mounted on the digital still camera. Since the recording capacity of the storage unit is limited, it is required to efficiently use the recording area of the storage unit. In addition, for the convenience of the user, it is also required to shorten the imaging time interval of each image during continuous shooting.
[0005]
Hereinafter, a conventional digital still camera will be described with reference to FIGS.
[0006]
First, the configuration of a conventional digital still camera will be described. FIG. 12 is a block diagram showing a configuration of a conventional digital still camera. Note that solid line arrows in the figure indicate transmission of image signals, and dotted line arrows indicate transmission of control signals. Hereinafter, each component in FIG. 12 will be described.
[0007]
First, the operation unit 101 is a shutter button or the like. When the user operates the operation unit 101, the operation unit 101 instructs the control unit 102 to perform continuous shooting.
[0008]
The control unit 102 includes an imaging unit 103, a first storage unit 104, a YC processing unit 105, a level measurement unit 106, a coefficient setting unit 107, a compression conversion unit 108, a code amount measurement unit 109, a scale factor setting unit 110, The recording unit 111 and the scratch correction calculation unit 112 are controlled.
[0009]
The imaging unit 103 includes an imaging element (not shown) such as a CCD, and converts an optical signal from an optical system part (not shown) into RGB three primary colors and converts the digitized electrical signal. When receiving an instruction from the control unit 102, the electrical signal is output to the first storage unit 104 and the level measurement unit 106.
[0010]
Further, the first storage unit 104 has a RAW / YC recording area 104a for recording the output of the imaging unit 103 and the output of the YC processing unit 105, and a compressed data recording area 104c for recording the output of the compression conversion unit 108. Also, under the control of the control unit 102, the RAW data recorded in the RAW / YC recording area 104a is stored in the scratch correction unit 112, the YC data recorded in the RAW / YC recording area 104a is stored in the compression conversion unit 108, and the compressed data recording area 104c. The data recorded in the above are output to the recording unit 111, respectively.
[0011]
Further, the YC processing unit 105 acquires the RAW / YC conversion calculation coefficient from the coefficient setting unit 107 and the RAW data from the defect correction unit 112 under the control of the control unit 102. Based on the calculation coefficient, the RAW data is converted to YC data, and the converted YC data is output to the RAW / YC recording area 104a. In addition, the defect correction unit 112 corrects a defect in the RAW data under the control of the control unit 102, and outputs the corrected RAW data to the YC processing unit 105.
[0012]
Here, the connection between the YC processing unit 105 and the scratch correction unit 112 will be described with reference to FIG. In FIG. 16, a YC processing unit 105 includes a YC calculation unit 105a and line memories 105b to 105f. The YC calculation unit 105a converts RAW data into YC data based on a RAW / YC conversion coefficient. Each of the line memories 105b to 105f records RAW data for one scanning line. The line memories 105b to 105f output to the YC calculation unit 105a. In addition to the outputs from the line memories 105b to 5f, the output from the defect correction unit 112 is input to the YC calculation unit 105a. Such a configuration is necessary because RAW data for six scanning lines is required at the same time when RAW / YC conversion is performed by the YC arithmetic unit 105a.
[0013]
The defect correction unit 112 includes a defect correction calculation unit 112a and line memories 112b to 112e, and the outputs of the line memories 112b to 112e and the first recording unit 104 are input to the defect correction calculation unit 112a. This configuration is necessary because the scratch correction unit 112 requires RAW data for five scanning lines at the same time for the scratch correction processing.
[0014]
The level measurement unit 106 includes a counter and the like, and acquires the output of the imaging unit 103, that is, RAW data, under the control of the control unit 102, and measures the level of the RAW data for each of the three primary colors of RBG.
[0015]
Also, the coefficient setting unit 107 calculates a calculation coefficient for RAW / YC conversion based on the measurement result of RAW data for one screen in the level measurement unit 106 under the control of the control unit 102, and temporarily stores the calculation coefficient therein. The calculation coefficient is output to the YC processing unit 105 as necessary.
[0016]
Further, the compression conversion unit 108 acquires the outputs of the RAW / YC recording area 104a and the scale factor setting unit 110 under the control of the control unit 102, and based on the outputs of the scale factor setting unit 110, the RAW / YC recording area 4a. YC data is compressed and converted, and the compressed data, that is, compressed data is output to the compressed data recording area 104 c and the code amount measuring unit 109.
[0017]
The code amount measuring unit 109 acquires compressed data from the compression conversion unit 108 under the control of the control unit 102 and measures the code amount of the compressed data, and is configured by a counter or the like.
[0018]
The scale factor measuring unit 110 calculates a scale factor based on the code amount for one screen measured by the code amount measuring unit 109, temporarily stores the scale factor therein, and a compression conversion unit as necessary. It outputs to 108.
[0019]
The recording unit 111 includes a flash memory or the like, acquires compressed data recorded in the compressed data recording area 104c under the control of the control unit 102, and records the compressed data.
[0020]
Next, an operation when recording image data for one screen of a conventional digital still camera will be described. FIG. 13 is a flowchart showing the operation of the control unit 102 when image data for one screen is recorded by a conventional digital still camera. Hereinafter, FIG. 13 will be described for each step.
[0021]
First, an optical signal from an optical system part (not shown) is input as an input image to the imaging unit 103, and the imaging unit 103 is controlled to convert the optical signal into RAW data. 1 is output to the storage unit 104 and the level measurement unit 106 (step S101).
[0022]
Next, by controlling the first storage unit 104, the RAW data that is the output of the imaging unit 103 is acquired, recording in the RAW / YC recording area 4a is started (step S102), and the level measuring unit 106 Is controlled to start the RGB level measurement of the RAW data that is the output of the imaging unit 103 (step S103).
[0023]
Next, the first storage unit 104 is controlled to transmit information indicating the amount of RAW data recorded in the RAW recording area to the control unit 102 (step S120). At this time, if the amount of RAW data recorded for one screen is based on the information, the process proceeds to step S109, and until that time, the process waits at step S120.
[0024]
Next, the coefficient setting unit 107 is controlled to obtain a total level for each RGB from the level measuring unit 106, calculate a calculation coefficient for RAW / YC conversion based on the level, and temporarily store the calculation coefficient therein. (Step S109).
[0025]
Next, the first storage unit 104 and the flaw correction unit 112 are controlled to cause the flaw correction unit 112 to acquire RAW data from the first storage unit 104 and to correct a defect in the RAW data, thereby correcting the YC processing unit 105. (Step S105), the first storage unit 104, the YC processing unit 105, the coefficient setting unit 107, and the scratch correction unit 112 are controlled, and the YC processing unit 105 sets the RAW data and the coefficient from the scratch correction unit 112. The calculation coefficient is acquired from the unit 107, RAW data is converted to YC data based on the calculation coefficient, and recorded in the RAW / YC data recording area 104b of the first storage unit 104 (step S106).
[0026]
Next, the first storage unit 104, compression conversion unit 108, code amount measurement unit 109, and scale factor setting unit 110 are controlled to perform the following operation (step S107). First, the scale factor setting unit 110 outputs the scale factor, and the first storage unit 104 outputs YC data. Next, based on the scale factor, the acquired YC data is compressed and converted by the compression conversion unit 108, and the compressed data obtained by the compression conversion is output to the code amount measurement unit 109. Next, the code amount measuring unit 109 measures the code amount based on the compressed data.
[0027]
Next, in step S108, the compression conversion unit 108 is controlled to monitor whether or not the compression conversion for one screen has been completed. When the compression conversion is completed, the process proceeds to step S110. In step S110, the code amount measurement unit 109 is monitored. And the scale factor setting unit 110 is controlled so that the code amount for one screen is acquired from the code amount measuring unit 109, the scale factor is calculated based on the code amount, and the scale factor is temporarily stored therein. .
[0028]
Next, the first storage unit 104, the scale factor setting unit 110, and the compression conversion unit 108 are controlled to cause the compression conversion unit 108 to acquire YC data, compress the YC data, and perform compression after compression conversion. Data is recorded in the compressed data recording area 104c (step S113).
[0029]
Finally, the compression conversion unit 108 is monitored to detect whether or not the compression conversion of YC data for one screen and the writing of the compressed data after the compression conversion to the first storage unit 104 have been completed. When the process is completed, the control by the control unit 102 for the imaging operation for one screen is ended (step S114).
[0030]
When compressed data for one image is stored in the first storage unit 104 by the operation of the conventional digital still camera, the compressed data can be reproduced at any time, and the compressed data is stored in the recording unit 111. Can be moved and used.
[0031]
Next, FIG. 14 which is a timing chart at the time of continuous shooting of the conventional digital still camera will be described. In FIG. 14, the horizontal axis is time. In addition, the time required in the following description is indicated on the horizontal axis as A, B, C, etc., respectively.
[0032]
FIG. 14A is a timing chart showing temporal changes in addresses to be accessed for RAW data and YC data. The vertical axis shows the address of the RAW / YC recording area 104a, and the upper and lower dotted lines in the figure are respectively shown. The upper limit and the lower limit of the address are shown, the thick arrow lines a101 and a106 indicate the locus of the RAW data write address, the thin arrow line a102 indicates the locus of the read address of the RAW data, and the thick arrow dotted line a103 indicates the writing of the YC data Shows the address trajectory, Thin arrow dotted line a104 and a105 indicate the locus of the read address of the YC data.
[0033]
FIG. 14C is a timing chart showing the time change of the operation state of the defect correcting unit 112. The upper and lower dotted lines in the figure indicate the correction processing state and the non-correction processing state, respectively, and the solid line indicates the correction processing. The locus of the state is shown. FIG. 14D is a timing chart showing the time change of the recording state of the compressed data. The upper and lower dotted lines in the drawing indicate the recording state and the non-recording state, respectively, and the solid line indicates the locus of the recording state. Show.
[0034]
Next, FIG. 15, which is a schematic diagram showing a change in storage state with time progress of the RAW / YC recording area 104 a of the first storage unit 104 in the conventional digital still camera, will be described. In FIG. 15, what is indicated by a square in the drawing is a schematic diagram of the RAW / YC recording area 104a.
[0035]
First, FIG. 15A shows a storage state from time A to time B in FIG. That is, from time A to time B, nothing is stored in the RAW / YC recording area 104a.
[0036]
Next, FIG. 15B shows a storage state immediately after time B in FIG. That is, it indicates that writing of RAW data to the RAW / YC recording area 104a is started at time B.
[0037]
Next, FIG. 15C shows a storage state at time C in FIG. That is, it indicates that writing of RAW data to the RAW / YC recording area 104a is completed at time C.
[0038]
Next, FIG. 15D shows the storage state immediately after time C in FIG. That is, it shows that reading of RAW data in the RAW / YC recording area 104a is started at time C.
[0039]
Next, FIG. 15E shows a storage state immediately after time D in FIG. That is, it indicates that writing of YC data is started in the RAW / YC recording area 104a at time D.
[0040]
Next, FIG. 15 (f) shows the storage state immediately after time E in FIG. That is, this indicates that reading of YC data in the RAW / YC recording area 104a is started at time E.
[0041]
Next, FIG. 15G shows a storage state at time H in FIG. That is, it indicates that reading of the YC data in the RAW / YC recording area 104a is completed at time H.
[0042]
Next, FIG. 15 (h) shows the storage state immediately after time I in FIG. That is, at time I, the RAW / YC recording area 104a RAW data writing Indicates that is started.
[0043]
As described above, the conventional digital still camera stores RAW data and YC data alternately in the same RAW / YC recording area 104a for each image. In this way, the usage amount of the recording area of the first storage unit 104 is saved.
[0044]
Next, the operation of the conventional digital still camera when continuous shooting is performed will be described with reference to FIGS.
[0045]
First, at time A in FIG. 14, when the user operates the operation unit 101, a continuous shooting operation is started, and the operation unit 101 instructs the control unit 102 to start continuous shooting. The storage state of the RAW / YC recording area 104a at this time is the state shown in FIG.
[0046]
When receiving an instruction to start the continuous shooting operation, the control unit 102 shifts to an imaging operation for the first screen. That is, the flow shifts to the operation shown in FIG. Then, the optical signal is converted into RAW data by the imaging unit 103 from time A to time B (step S101). Next, at time B, the process proceeds to step S102, and the RAW data is written in the RAW / YC recording area 104a (track a101 in FIG. 14), and the process proceeds to step S103, and the level measurement unit 106 measures the level of the RAW data. Start. Then, immediately after time B, the RAW / YC recording area 104a is in the state shown in FIG.
[0047]
Next, in step S120, it is detected whether or not writing of RAW data is completed. When writing of RAW data (trajectory a101 in FIG. 14) is completed at time C, the process proceeds to step S109, and the coefficient setting unit 107 performs RAW data writing. / YC conversion calculation coefficient is set. The RAW / YC recording area 104a at this time is in the state shown in FIG.
[0048]
Here, calculation of the calculation coefficient in the coefficient setting unit 107 is performed after the level measurement unit 106 has measured the RAW data for one screen with the calculation coefficient necessary for the RAW / YC conversion being one screen. This is because it must be determined according to the overall brightness and color tone, and must be set based on RAW data for one screen.
[0049]
Next, at time C, RAW data is read from the first storage unit 104 (track a102 in FIG. 14), defect correction is started (step S105), and at time D, the process proceeds to step S106, and YC The processing unit 105 converts the RAW data into YC data, and starts writing the YC data in the RAW / YC recording area 104a (trajectory a103 in FIG. 14). The RAW / YC recording area 104a is in the state shown in FIG. 15D immediately after time C, and in the state shown in FIG.
[0050]
Here, in order to convert RAW data into YC data, it is necessary to use the calculation coefficient based on the calculation coefficient. After the level measurement unit 106 measures RAW data for one screen as described above, the calculation coefficient is calculated. You can't get it without it. Therefore, YC data can be generated only after the writing of the RAW data to the first storage unit 104 (the locus a101 in FIG. 14) is completed.
[0051]
Next, at time E, YC data is read from the RAW / YC recording area 104a to the compression conversion unit 108 (trajectory a104 in FIG. 14), converted into compressed data, and the code amount of the compressed data is converted into a code amount measurement unit 109. (Step S107). Then, immediately after time E, the RAW / YC recording area 104a is in the state shown in FIG.
[0052]
Next, in step S108, the compression conversion unit 108 is controlled to monitor whether or not the compression conversion for one screen has been completed. As a result, when it is detected that the compression conversion for one screen has been completed, the process proceeds to time H. The process proceeds to S110, where the scale factor setting unit 110 sets the scale factor based on the code amount measured by the code amount measuring unit 109. At the same time, the YC data is again read from the RAW / YC recording area 104a (track a105 in FIG. 14), and the YC data is converted into compressed data based on the scale factor set by the scale factor setting unit 110. The compressed data is recorded in the compressed data recording area 104c (step S113). Note that the RAW / YC recording area 104a is in the state shown in FIG. 15G at time H, and in the state shown in FIG.
[0053]
Next, reading of the second YC data on the first screen is completed at time J (trajectory a105 in FIG. 14), and immediately after that, recording of the compressed data on the first screen in the compressed data recording area 104c is completed. On the other hand, writing of RAW data for the second screen at time I (trajectory a106 in FIG. 14) starts, and thereafter the same operation as for the first screen is performed. The same operation is performed for the third and subsequent screens, and the photographing operation is repeated for a predetermined number of screens. At time K, the RAW / YC recording area 104a is again in the state shown in FIG.
[0054]
As described above, the conventional digital still camera realizes the continuous shooting function while saving the storage capacity of the first storage unit by alternately recording RAW data and YC data in the same recording area. ing.
[0055]
[Problems to be solved by the invention]
However, the above-described conventional configuration has a problem in that the time required for the continuous shooting operation cannot be shortened because YC data cannot be generated until RAW data writing is completed. That is, it is difficult to shorten the time from the start of writing RAW data for the next input image after the writing of RAW data for an arbitrary input image to the first storage unit 104 is completed.
[0056]
Here, with the conventional digital still camera, YC data cannot be generated until RAW data has been written, as described above, after the calculation coefficient is measured by the level measuring unit 106 for RAW data for one screen. This is because, in order to convert RAW data into YC data, the calculation coefficient must be used.
[0057]
Another problem is that the capacity of the RAW / YC recording area 104a must be increased. This is because when RAW data is converted to YC data, the number of bits per pixel increases, so when RAW data and YC data are stored in the same recording area as in a conventional digital still camera, only RAW data is stored. This is because it becomes larger than the case where it is performed.
[0058]
In the interface portion of the first storage unit 104, RAW data reading / writing, YC data reading / writing, and the like between the imaging unit 103, the YC processing unit 105, the compression conversion unit 108, the recording unit 111, and the scratch correction unit 112 are performed. Since the reading and writing of the compressed data is concentrated, the access to the first storage unit 104 becomes a bottleneck, and there is a problem that the signal processing speed of the entire digital still camera becomes slow.
[0059]
SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems, and to provide a digital still camera that can reduce the operation time required for continuous shooting.
[0060]
[Means for Solving the Problems]
In order to achieve this object, a digital still camera of the present invention includes an imaging unit that converts an optical signal indicating an input image into RAW data, RAW data YC processing unit for converting into YC data, compression conversion unit for converting YC data converted by YC processing unit into compressed data, and compression coefficient based on the compressed data converted by the compression conversion unit Code amount estimation A compression coefficient setting unit; RAW data generated by the imaging unit is stored, and YC data corresponding to the stored RAW data is stored in a storage area different from the RAW data A storage unit; The code amount estimation by the compression coefficient setting unit is performed overlapping with the operation of writing the RAW data to the storage unit, When the compression coefficient setting unit calculates the compression coefficient, Memory The YC processing unit is controlled so that the RAW data stored in is read and converted into YC data again. YC processing unit And a control unit that controls the compression conversion unit so as to convert the YC data converted again in step S3 into compressed data again based on the compression coefficient calculated by the compression coefficient setting unit.
[0061]
With this configuration, in addition to being able to obtain an image that is comparable to an image that can be obtained with a conventional digital still camera, it has the effect of reducing the operating time required for continuous shooting. .
[0062]
DETAILED DESCRIPTION OF THE INVENTION
According to the first aspect of the present invention, an imaging unit that converts an optical signal indicating an input image into RAW data; RAW data YC processing unit for converting into YC data, compression conversion unit for converting YC data converted by YC processing unit into compressed data, and compression coefficient based on the compressed data converted by the compression conversion unit Code amount estimation A compression coefficient setting unit; RAW data generated by the imaging unit is stored, and YC data corresponding to the stored RAW data is stored in a storage area different from the RAW data A storage unit; The code amount estimation by the compression coefficient setting unit is performed overlapping with the operation of writing the RAW data to the storage unit, When the compression coefficient setting unit calculates the compression coefficient, Memory The YC processing unit is controlled so that the RAW data stored in is read and converted into YC data again. YC processing unit And a control unit that controls the compression conversion unit so as to convert the YC data converted again in step 1 into compression data again based on the compression coefficient calculated by the compression coefficient setting unit. YC data can be generated before writing is completed, so that it is possible to obtain images that are comparable in quality to images that can be obtained with conventional digital still cameras, and shorten the operating time required for shooting. Can be realized.
[0063]
According to a second aspect of the present invention, an imaging unit that converts an optical signal indicating an input image into RAW data; RAW data By calculating a compression coefficient based on the YC processing unit for converting to YC data, the compression conversion unit for converting the YC data converted by the YC processing unit into compressed data, and the compressed data converted by the compression conversion unit Perform code amount estimation A compression coefficient setting unit; RAW data generated by the imaging unit is stored A first storage unit; Store YC data corresponding to the stored RAW data in a storage area different from the RAW data A second storage unit; The code amount estimation by the compression coefficient setting unit is performed in duplicate with the operation of writing the RAW data to the first storage unit, When the compression coefficient setting unit calculates the compression coefficient, the YC processing unit is controlled to read out the RAW data stored in the first storage unit and convert it to YC data again. YC processing unit And a control unit that controls the compression conversion unit so as to convert the YC data converted again in step 1 into compression data again based on the compression coefficient calculated by the compression coefficient setting unit. Since the YC data is not stored in the first storage unit that stores the data, it is possible to prevent the access speed from being concentrated on the first storage unit and the processing speed of the entire digital still camera from being slowed, and the storage of the first storage unit This has the effect of reducing the capacity used in the area.
[0064]
According to a third aspect of the present invention, there is provided the digital still camera according to the second aspect, wherein a circuit constituting the second storage unit, a control unit, a circuit constituting the YC processing unit and the compression conversion unit are provided. Is configured on a single semiconductor chip, which can reduce the power required for access between the second storage unit and the control unit, and can reduce the time required for access. Has the effect of being able to.
[0065]
According to a fourth aspect of the present invention, an imaging unit that converts an optical signal indicating an input image into RAW data composed of a plurality of color signals, RAW data A calculation coefficient setting unit that calculates a calculation coefficient used when YC data is generated by mixing a plurality of color signals; RAW data Based on the YC processing unit that converts YC data based on the calculated calculation coefficient, the compression conversion unit that converts the YC data converted by the YC processing unit into compressed data, and the compressed data converted by the compression conversion unit Calculate compression factor Code amount estimation A compression coefficient setting unit; RAW data generated by the imaging unit is stored, and YC data corresponding to the stored RAW data is stored in a storage area different from the RAW data A storage unit; The code amount estimation by the compression coefficient setting unit is performed overlapping with the operation of writing the RAW data to the storage unit, When the compression coefficient setting unit calculates the compression coefficient, Memory The YC processing unit is controlled so that the RAW data stored in the data is read and converted into YC data again based on the calculation coefficient set by the calculation coefficient setting unit. YC processing unit And a control unit that controls the compression conversion unit so as to convert the YC data converted again in step 1 into compressed data based on the compression coefficient calculated by the compression coefficient setting unit. Since the calculation coefficient of the RAW / YC conversion is calculated based on the distribution of the YC data, the distribution of the YC data converted based on the calculation coefficient can be controlled with high accuracy.
[0066]
The invention according to claim 5 of the present invention is the digital still camera according to claim 4, wherein the YC processing unit inputs the input image based on the calculation coefficient set by the calculation coefficient setting unit. RAW data corresponding to the next input image of the image is converted into YC data, and YC data without white crushing can be obtained.
[0067]
The invention according to claim 6 of the present invention is the digital still camera according to claim 4, wherein the YC processing unit suppresses the amplitude of the luminance signal or color signal of the calculation coefficient calculated by the calculation coefficient setting unit. The RAW data converted by the imaging unit corresponding to the input image next to the input image is converted into YC data based on the corrected calculation coefficient. Saturation and white crushing at the maximum value of YC data can be prevented.
[0068]
A seventh aspect of the present invention is the digital still camera according to any one of the first to sixth aspects, Memory or During the period in which the first storage unit stores the RAW data converted by the imaging unit, the YC processing unit , Memory or It is characterized by starting to convert the RAW data stored in the first storage unit into YC data. Since YC data can be generated before the writing of the RAW data is completed, it is necessary for continuous shooting operation. It has the effect that the time can be shortened.
[0069]
The invention according to claim 8 of the present invention is the digital still camera according to any one of claims 1 to 7, wherein the digital still camera includes a scratch correction calculation unit that corrects a defect in RAW data, and the YC processing unit is RAW data. A line memory for temporarily storing a part of the data, and the defect correction calculation unit reads out the RAW data stored in the line memory and sequentially corrects defects in the read RAW data In addition, since the defect correction calculation unit and the YC processing unit share the line memory, there is an effect that the scale of the circuit for realizing the digital still camera according to the present invention can be reduced.
[0070]
The invention according to claim 9 of the present invention is the digital still camera according to any one of claims 1 to 8, Memory or The first storage unit divides the RAW data indicating the input image into a plurality of small images and outputs them, and the YC processing unit , Memory or The RAW data for each small image output from the first storage unit is converted into YC data, and the YC processing unit performs processing for each small image, so that the circuit constituting the YC processing unit It has the effect that the scale of the can be reduced.
[0071]
A tenth aspect of the present invention is the digital still camera according to any one of the first to ninth aspects, wherein the YC processing section is , Memory or A part of the RAW data stored in the first storage unit is converted into YC data, the compression conversion unit converts the YC data converted by the YC processing unit into compressed data, and the compression coefficient setting unit is the compression conversion unit. The compression coefficient is set based on the converted compressed data, and RAW / YC conversion and compression conversion for calculating the compression coefficient can be completed in a short time. The operation time required for shooting can be shortened.
[0072]
(Embodiment 1)
A digital still camera according to Embodiment 1 of the present invention will be described below with reference to FIGS.
[0073]
First, the configuration of the digital still camera according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a digital still camera according to Embodiment 1 of the present invention. Note that solid line arrows in the figure indicate transmission of image signals, and dotted line arrows indicate transmission of control signals. Hereinafter, each component in FIG. 1 will be described.
[0074]
First, the operation unit 1 is a shutter button or the like. When the user operates the operation unit 1, the operation unit 1 instructs the control unit 2 to perform continuous shooting. The control unit 2 includes an imaging unit 3, a first storage unit 4, a YC processing unit 5, a level measurement unit 6, a coefficient setting unit 7, a compression conversion unit 8, a code amount measurement unit 9, a scale factor setting unit 10, The recording unit 11 and the scratch correction calculation unit 12 are controlled.
[0075]
The imaging unit 3 includes an imaging element (not shown) such as a CCD, and converts an optical signal from an optical system part (not shown) into RGB three primary colors and converts the digitized electrical signal. When receiving an instruction from the control unit 2, the electrical signal is output to the first storage unit 4 and the level measurement unit 6. In the present specification, the electric signal output from the imaging unit 3 is referred to as RAW data.
[0076]
The first storage unit 4 includes a DRAM (dynamic random access memory) or the like, and includes a RAW recording area 4a for recording the output of the imaging unit 3, that is, RAW data, and a YC recording area 4b for recording the output of the YC processing unit 5. And a compressed data recording area 4 c for recording the output of the compression conversion unit 8. Further, under the control of the control unit 2, the data recorded in the RAW recording area 4a is recorded in the YC processing unit 5, the data recorded in the YC recording area 4b is recorded in the compression converting unit 8, and the data recorded in the compressed data recording area 4c is recorded. Output to the unit 11.
[0077]
Further, the YC processing unit 5 acquires the RAW / YC conversion calculation coefficient from the coefficient setting unit 7 and the RAW data from the RAW recording area 4 a of the first storage unit 4 under the control of the control unit 2. Then, based on the calculation coefficient, the RAW data is converted into YC data. Further, the RAW data temporarily stored in the YC processing unit 5 during the conversion process is output to the defect correction calculation unit 12, and the converted YC data is output to the YC recording area 4b. YC data refers to a signal obtained by superimposing a luminance signal (Y signal) and a color signal (C signal).
[0078]
In addition, the defect correction calculation unit 12 corrects a defect in the RAW data under the control of the control unit 2, and outputs the corrected RAW data to the RAW recording area 4a. Here, the connection between the YC processing unit 5 and the scratch correction calculation unit 12 will be described with reference to FIG. In FIG. 4, a YC processing unit 5 includes a YC calculation unit 5a and line memories 5b to 5f. The YC calculation unit 5a converts RAW data into YC data based on a RAW / YC conversion coefficient. The line memories 5b to 5f each record RAW data for one scanning line. The line memories 5b to 5f output the YC calculation unit 5a and the defect correction calculation unit 12, respectively. In addition to the outputs of the line memories 5b to 5f, the output of the first storage unit 4 is input to the YC calculation unit 5a. Such a configuration is necessary because RAW data for six scanning lines is required at the same time when RAW / YC conversion is performed by the YC calculation unit 5a, and the defect correction calculation unit 12 performs defect correction processing. This is because RAW data for five scanning lines is required at the same time. With the above configuration, since the line memories (line memories 5b to 5f) necessary for RAW / YC conversion can be used also as the line memories necessary for defect correction, the configuration can be simplified.
[0079]
Further, in a digital still camera whose resolution is remarkably increased, the number of pixels in one horizontal section may reach several thousand, so that the line memory consumes a very large number of transistors. Therefore, it is very effective to share the line memory used for YC processing and the line memory used for defect correction, and delete one of them. Further, when a technique for processing an input image by dividing it into a plurality of small images is used here, the required line memory capacity is proportional to the number of pixels in one horizontal section of the small image, and the pixels in one horizontal section of the input image. Since it is independent of the number, the input image is divided into small portions in the horizontal direction and processed, thereby reducing the capacity of the line memory used for YC processing and defect correction, and greatly reducing the number of transistors constituting the line memory. I can do it. In addition to reducing the line memory capacity, the storage capacity of the YC recording area 4b is proportional to the number of pixels in one horizontal section. Therefore, by using a method of dividing an image into small images, the YC recording area 4b The circuit scale can be greatly reduced.
[0080]
The level measuring unit 6 includes a counter and the like. The level measuring unit 6 acquires the output of the imaging unit 3, that is, RAW data, under the control of the control unit 2, and measures the level of the RAW data for each of the three primary colors of the RBG. Also, the coefficient setting unit 7 calculates a calculation coefficient for RAW / YC conversion based on the measurement result of RAW data for one screen in the level measurement unit 6 under the control of the control unit 2, and temporarily stores the calculation coefficient therein. The calculation coefficient is output to the YC processing unit 5 as necessary. Here, the calculation coefficient of RAW / YC conversion is a calculation coefficient used when mixing RGB signals, and is set so that the brightness and color tone of the screen in YC data are appropriate based on the calculation coefficient. . The calculation coefficient setting unit includes a level measurement unit 6 and a coefficient setting unit 7.
[0081]
Further, the compression conversion unit 8 acquires the outputs of the YC recording area 4b and the scale factor setting unit 10 under the control of the control unit 2, and outputs the YC recording area 4b based on the output of the scale factor setting unit 10. The YC data is subjected to compression conversion, and the data after the compression conversion, that is, the compressed data is output to the compressed data recording area 4c and the code amount measuring unit 9. Here, the compression conversion method is, for example, JPEG. In the case of JPEG compression, the macroblock of YC data of 16 horizontal pixels and 8 vertical pixels is read out as a unit for compression conversion. Note that the data amount of the compressed data, that is, the code amount increases or decreases depending on the scale factor.
[0082]
The code amount measuring unit 9 acquires compressed data from the compression conversion unit 8 under the control of the control unit 2 and measures the code amount of the compressed data, and includes a counter and the like. The scale factor measuring unit 10 calculates the scale factor based on the code amount for one screen measured by the code amount measuring unit 9, temporarily stores the scale factor therein, and compresses and converts the scale factor as necessary. 8 is output. The scale factor is a parameter for controlling the amount of code generated in the compression conversion. The compression coefficient setting unit includes a code amount measurement unit 9 and a scale factor setting unit 10.
[0083]
The recording unit 11 includes a flash memory or the like, acquires compressed data recorded in the compressed data recording area 4c under the control of the control unit 2, and records the compressed data. The recording unit 11 may be incorporated in the digital still camera according to Embodiment 1 of the present invention, or may be a memory card that can be attached to and detached from the digital still camera according to Embodiment 1 of the present invention. .
[0084]
Next, an operation of recording image data for one screen of the digital still camera according to Embodiment 1 of the present invention will be described with reference to FIG. FIG. 2 is a flowchart showing the operation of the control unit 2 when image data for one screen is recorded by the digital still camera according to Embodiment 1 of the present invention.
[0085]
First, an optical signal from an optical system part (not shown) is input to the imaging unit 3, and the imaging unit 3 is controlled to convert the optical signal into RAW data, and the RAW data is stored in the first storage. The output is made to the unit 4 and the level measuring unit 6 (step S1). Next, by controlling the first storage unit 4, RAW data that is an output of the imaging unit 3 is acquired and recording in the RAW recording area 4 a is started (step S <b> 2). Next, the level measurement unit 6 is controlled to start RGB level measurement of the RAW data that is the output of the imaging unit 3 (step S3).
[0086]
Next, the first storage unit 4 is controlled to transmit information indicating the recording amount of the RAW data in the RAW recording area to the control unit 2 (step S4). At this time, when the recording amount of the RAW data becomes 6 lines or more, the process proceeds to step S5, and until that time, the process waits at step S4.
[0087]
Next, the first storage unit 4, the YC processing unit 5, the coefficient setting unit 7, and the flaw correction calculation unit 12 are controlled to convert the RAW data into YC data, and at the same time, correct defects in the RAW data (step S5). ). At this time, the YC processing unit 5 is caused to acquire the raw data from the first storage unit 4 and the calculation coefficient from the coefficient setting unit 7, convert the raw data to YC data based on the calculation coefficient, and perform the first storage. It is recorded in the YC data recording area 4b of the section 4. In addition, the scratch correction calculation unit 12 acquires RAW data from the YC processing unit 5, corrects defects in the RAW data, and outputs only the corrected portion of the RAW data to the first storage unit 4. The corrected RAW data is recorded in the RAW recording area 4a of the first storage unit 4.
[0088]
Here, the operation of flaw correction will be described with reference to FIG. FIG. 5 is a diagram showing an example of an array of RAW data for each line. In FIG. 5, Aa to Ea represent RGB pixel data, and the hatched pixels are darker than the non-hatched pixels. The pixel Cc is a pixel having a flaw, that is, a defect. At this time, the pixel Cc is complemented using neighboring pixels Ac, Ca, Ce, and Ec of the same color. Hereinafter, the reason for complementing using the pixels Ac, Ca, Ce, and Ec, that is, the reason why the line memories 5b to 5f are required for complementation will be described. First, in addition to the complementing method in the first embodiment of the present invention, as a simple defect correction method that does not require a line memory, the pixels Ca and Ce in the same line, that is, the pixels Ca and Ce in FIG. There is a way to complement with the value. However, in this method, when the pixel Ce is at a luminance change point as shown in FIG. 5, if the pixel Ce is used for complementation, the luminance of the pixel Cc is significantly different from the surrounding pixels and becomes unnatural. Therefore, if the line memories 5b to 5f are used as shown in FIG. 4, the upper and lower pixels Ac and Ec can also be used for complementation. By using an algorithm such as “an average value of two pixels is used as a complementary value of a scratch pixel”, natural complementation is possible even when there is an edge with a large luminance difference in the vicinity.
[0089]
Next, the YC processing unit 5 is monitored, and when RAW / YC conversion of RAW data for one macroblock that can be converted by the compression conversion unit 8, RAW / YC conversion is performed (step S6). In JPEG conversion, one macro block corresponds to RAW data of 16 horizontal pixels × 8 vertical pixels.
[0090]
Here, the monitoring of the YC processing unit 5 will be described with reference to FIG. FIG. 6 is a schematic diagram showing the YC recording area 4b. Portions delimited by horizontal lines indicated by dotted lines indicate YC data recording areas for each scanning line. Therefore, the YC recording area 4b can record YC data of 16 scanning lines. A portion indicated by hatching in the figure is a portion where RAW / YC conversion is completed and YC data is recorded. As shown in the figure, the recording area 4b always records the latest YC data in the FIFO format. As described above, in the case of JPEG conversion, when YC data of 16 pixels × 8 pixels or more is recorded, the process proceeds to step S7.
[0091]
Next, in step S7, the first storage unit 4, compression conversion unit 8, code amount measurement unit 9, and scale factor setting unit 10 are controlled to perform the following operation. First, the scale factor setting unit 10 outputs the scale factor, and the first storage unit 4 outputs the YC data. Next, based on the scale factor, the obtained YC data is compressed and converted by the compression conversion unit 8, and the compressed data obtained by the compression conversion is output to the code amount measurement unit 9. That is, the total number of bits of the compressed data is measured.
[0092]
Here, referring to FIG. 6 again, the recording and reading states of the YC recording area 4b during compression conversion will be described. First, compression conversion starts when YC data for one macroblock capable of compression conversion is recorded in the YC recording area a, and before the new recording of YC data is completed in the YC recording area b, the YC recording area a The YC data compression conversion is completed. Similarly, compression conversion starts when YC data for one macroblock capable of compression conversion is recorded in the YC recording area b, and before the new recording of YC data is completed in the YC recording area a, the YC recording area The compression conversion of the YC data of b is completed. Thereafter, this operation is repeated until the compression conversion for one screen is completed.
[0093]
Next, in step S8, the level measuring unit 6 and the compression conversion unit 8 are controlled to monitor whether or not the compression conversion for one screen has been completed, and when completed, the process proceeds to step S9, where the coefficient setting unit 7 To obtain the total level for each RGB from the level measurement unit 6, calculate the RAW / YC conversion calculation coefficient based on the level, and temporarily store the calculation coefficient inside.
[0094]
Next, when the compression conversion unit 8 completes the compression conversion for code amount estimation, the code amount measurement unit 9 and the scale factor setting unit 10 are controlled, and the code amount for one screen is controlled from the code amount measurement unit 9. Is obtained, the scale factor is calculated based on the code amount, and the scale factor is temporarily stored therein (step S10). Next, the first storage unit 4, the coefficient setting unit 7, and the YC processing unit 5 are controlled to acquire the RAW data from the first storage unit 4 and the RAW / YC conversion calculation coefficient from the coefficient setting unit 7. Then, the RAW data is converted into YC data based on the calculation coefficient, and written into the recording area 4a of the first storage unit 4 (step S11).
[0095]
Next, in step S12, similarly to step S6, the YC processing unit 5 is monitored, and when RAW data for one macroblock is RAW / YC converted, the process proceeds to step S13, and the first storage unit 4, The scale factor setting unit 10 and the compression conversion unit 8 are controlled so that the compression conversion unit 8 acquires YC data and a scale factor, and the acquired YC data is compression converted based on the scale factor. Data is recorded in the compressed data recording area 4c.
[0096]
Finally, in step S14, the compression conversion unit 8 is monitored to detect whether the compression conversion of YC data for one screen and the writing of the compressed data after the compression conversion to the first storage unit 4 have been completed. When these are finished, the control by the control unit 2 for the image pickup operation for one screen is finished.
[0097]
Here, the reason why the code amount is estimated in step S7 will be described. The compressed data recorded in the first storage unit 4 is finally stored in the recording unit 11. However, since the recording capacity of the recording unit 11 is limited, a predetermined image is recorded. It is necessary to strictly adjust the code amount of the compressed data for each image. Here, since the data amount of the compressed data depends on the scale factor, it is necessary to adjust the scale factor in order to strictly adjust the code amount of the compressed data for each image. Therefore, step S7, which is a step for measuring the code amount after compression conversion and compression conversion for adjusting the scale factor, is necessary. Since the compression conversion in step S7 is for code amount estimation, the generated compressed data itself is not output to the first storage unit 4, but only the number of bits of the generated compressed data is integrated.
[0098]
Next, FIG. 3 which is a timing chart at the time of continuous shooting of the digital still camera according to Embodiment 1 of the present invention will be described. In FIG. 3, the horizontal axis is time. In addition, the time required in the following description is indicated on the horizontal axis as A, B, C, etc., respectively.
[0099]
Further, (a) is a diagram showing the time change of the address for accessing the RAW data, the vertical axis indicates the address of the RAW recording area 4a, and the upper and lower dotted lines in the figure indicate the upper limit and the lower limit of the address, respectively. The thick arrow lines a1, a4, and a7 indicate the locus of the write address of the RAW data, and the thin arrow lines a2, a3, a5, a6, and a8 indicate the locus of the read address of the RAW data.
[0100]
Further, (b) is a diagram showing the time change of the recording state of the YC data, the upper and lower dotted lines in the figure respectively indicate the recording state and the non-recording state, the solid line indicates the locus of the recording state, and b1 Is the first time on the first screen, b2 is the second time on the first screen, b3 is the first time on the second screen, b4 is the second time on the second screen, and b5 is the first time after the RAW / YC conversion on the third screen. YC data is shown respectively.
[0101]
Further, (c) is a diagram showing the time change of the operation state of the scratch correction calculation unit 12, in which the upper and lower dotted lines indicate the correction processing state and the non-correction processing state, respectively, and the solid line indicates the state of the correction processing Shows the trajectory. Further, (d) is a diagram showing the time change of the recording state of the compressed data, the upper and lower dotted lines in the figure indicate the recording state and the non-recording state, respectively, and the solid line indicates the locus of the recording state.
[0102]
Next, the operation of the digital still camera according to Embodiment 1 of the present invention when continuous shooting is performed will be described below with reference to FIGS.
[0103]
First, at time A in FIG. 3, when the user operates the operation unit 1, a continuous shooting operation is started, and the operation unit 1 instructs the control unit 2 to start continuous shooting. When receiving an instruction to start the continuous shooting operation, the control unit 2 shifts to an imaging operation for the first screen. That is, the flow shifts to the operation shown in FIG. Then, the optical signal is converted into RAW data by the imaging unit 3 from time A to time B (step S1). The interval between time A and time B is about 2/60 seconds, for example.
[0104]
Next, at time B, the process proceeds to step S2, and the RAW data is written into the RAW recording area 4a (the locus a1 in FIG. 3). At the same time, the process proceeds to step S3 and the level measurement unit 6 starts measuring the level of the RAW data To do. Next, when RAW data for 6 scanning lines is written in the RAW recording area 4a at time C, this is detected in step S4, and the process proceeds to step S5. As a result, from time C to time E, RAW data is read from the RAW recording area 4a (track a2 in FIG. 3), and YC data after RAW / YC conversion is recorded in the YC recording area 4b (track b1 in FIG. 3). . At the same time, flaw correction is also performed in the flaw correction calculation unit 12, and at time E, the RAW data is corrected for defects. Further, the process proceeds to step S7 with a slight delay from time C.
[0105]
Here, the interval between the time B and the time D, that is, the RAW data write time is about 12/60 seconds. This RAW data write time is the access time at the time of writing in the first storage unit 4 or the control unit. 2. It depends on the signal processing capability of the imaging unit 3 and the like. Since the RAW data and the YC data are recorded in different recording areas, the RAW data can be held even if YC data necessary for code amount estimation is generated. For this reason, the code amount can be estimated in an overlapping manner with the RAW data writing operation, and as a result, the operation time required for imaging can be shortened. Further, the gradient of the address writing locus a1 and the address reading locus a2 in FIG. 3 is the same, but this is because the reading speed of the RAW data is controlled by the control unit 2 so that the two loci do not intersect. In other words, the corresponding recording area of the RAW recording area 4a is not read before writing the RAW data.
[0106]
Next, at time E, when the first reading of the RAW data (trajectory a2 in FIG. 3) is completed, immediately after that, the process proceeds from step S8 to step S9 and step S10 to step S11. In step S11, the RAW data is read from the RAW recording area 4a (trajectory a3 in FIG. 3), and the RAW data is converted into YC data and recorded in the YC recording area 4b (trajectory b2 in FIG. 3).
[0107]
Note that the gradients of the trajectories a3, a5, a6, and a8 are steeper than the gradient of the trajectory a2. This is to shorten the time required for the continuous shooting operation. That is, after the writing of the first RAW data is completed, the writing of the next second RAW data is started immediately after the exposure time of the imaging unit 3, and the second RAW data is started from the writing start of the first RAW data. This is because it is necessary to read out the first RAW data twice until the writing operation is completed so that the respective reading operations do not overlap. The processing performance of the YC processing unit 5 and the compression conversion unit 8 is optimally designed in order to achieve the reading speed of the RAW data related to the trajectories a3, a5, a6, and a8. It is technically possible.
[0108]
Next, at time F, compressed data is generated and recorded in the compressed data recording area 4c (step S13). It should be noted that the scratch correction of the RAW data and the level measurement of the RAW data are performed before the time E at which the generation of the necessary YC data is started in step S13. Therefore, the YC data required in step S13 is the RAW data corrected with the scratch correction and the RAW data. This can be obtained based on the optimized RAW / YC conversion calculation coefficient. Further, the scale factor in step S13 is optimized by code amount estimation. Therefore, an image composed of compressed data obtained by using these YC data and scale factor has the same quality as an image of a conventional digital still camera, and the compressed data can be set to a desired code amount. it can.
[0109]
Next, generation of the second YC data for the first screen is completed at time H (trajectory b2 in FIG. 3), and recording of the compressed data for the first screen in the compressed data recording area 4c is completed at time I. Here, the interval between time E and time H, that is, the RAW data read time is about 3/40 seconds, and this RAW data read time is the access time at the time of reading from the first storage unit 4 or the control unit. Depends on signal processing capability of 2 etc.
[0110]
On the other hand, the imaging operation for the second screen starts at time D, and thereafter operates similarly to the first screen. However, YC data is always read after the previous YC data read operation is completed. At this time, while the RAW / YC conversion and the compression conversion are being performed for the first screen, writing of the RAW data of the second screen to the first storage unit 4 is started, but the RAW data of the first screen of the address to be overwritten. Is already read and processed, so there is no problem.
[0111]
In this way, while the imaging operations of the previous and subsequent screens are overlapped, the same operation as described above is repeated thereafter, and the continuous shooting operation ends when the shooting of a predetermined number of screens is completed. Here, the overlap of the shooting operations of the front and rear screens means a state where the shooting of the front and rear screens is processed simultaneously. For example, the first screen and the second screen are captured between time D and time I. The operation is duplicated.
[0112]
Note that the recording of the compressed data to the recording unit 11 starts at time F and is recorded in order from the first screen to the final screen. In general, since the recording speed to the recording unit 11 is slow, the recording to the recording unit 11 often continues even after the continuous shooting operation ends.
[0113]
As described above, according to Embodiment 1 of the present invention, the following effects can be obtained.
[0114]
First, in addition to being able to obtain an image that is comparable to an image that can be obtained with a conventional digital still camera, it is possible to realize a reduction in operation time required for photographing.
[0115]
This is due to the following reason. That is, the RAW data stored in the first storage unit 4 is converted into YC data by the YC processing unit 5 (step S5), and the YC data converted by the YC processing unit 5 is converted into compressed data by the compression conversion unit 8. After converting (step S7) and setting the scale factor by the scale factor setting unit 10 based on the compressed data converted by the compression conversion unit 8 (step S10), the first storage unit 4 is controlled by the control unit 2 The RAW data stored in step S11 is converted again to YC data by the YC processing unit 5 (step S11), and the YC data converted again by the YC conversion unit 5 is based on the scale factor set by the scale factor setting unit 10. Since the compression conversion unit 8 converts the data into compressed data (step S13), the YC data in step S5 necessary for code amount estimation is converted. Even form, it is not necessary to hold the entire YC data. Therefore, there is no need to erase the RAW data by overwriting the YC data in the recording area where the RAW data is recorded as in the conventional digital still camera, so the RAW data is held in the first storage unit 4. be able to. Therefore, in the conventional digital still camera, the RAW / YC conversion is performed after the RAW data writing operation is completed, and the code amount is estimated. However, the code amount estimation overlaps with the RAW data writing operation. Will be able to do. As a result, the operation time required for imaging can be shortened. On the other hand, since the scratch correction of RAW data and the level measurement of the RAW data are performed before the YC data required in step S13 is generated in step S11, the YC data required in step S13 is the RAW data corrected and optimized. Can be obtained based on the calculated RAW / YC conversion coefficient. As a result, the image composed of the compressed data obtained by using the YC data generated in step S11 has the same quality as the image of the conventional digital still camera. As described above, according to the present invention, in addition to being able to obtain an image that is comparable to an image that can be obtained with a conventional digital still camera, it is possible to realize a reduction in operation time required for shooting. It is.
[0116]
Second, the RAW data stored in the first storage unit 4 is converted into YC data by the YC processing unit 5 (step S5), and the YC data converted by the YC processing unit 5 is compressed by the compression conversion unit 8. The data is converted into data (step S7), the scale factor is set by the scale factor setting unit 10 based on the compressed data converted by the compression conversion unit 8 (step S10), and then the first storage is performed under the control of the control unit 2. The RAW data stored in the unit 4 is converted again into YC data in the YC processing unit 5 (step S11), and the YC data converted again in the YC conversion unit 5 is converted into the scale factor set in the scale factor setting unit 10. Based on this, the compression conversion unit 8 converts the data into compressed data (step S13), so that YC data necessary for code amount estimation is generated in step S5. Also, because the need to retain the entire YC data is eliminated, it is possible to save the recording area of the first storage unit 4 by that amount.
[0117]
Third, the scale of the circuit for realizing the digital still camera according to the present invention by the defect correction calculation unit 12 sequentially correcting defects in the RAW data recorded in the line memories 5b to 5f of the YC processing unit 5. Can be reduced. Since the YC data used in step S7 and the YC data used in step S13 are generated separately, even if the scratch correction calculation unit 12 and the YC processing unit 5 share the line memories 5b to 5f, the processing is performed. There is no demerit in terms of time or image quality. Further, although the YC data used in step S7 includes defects, since the frequency of defects is about several per 10,000 pixels, there is no problem in performing the code amount estimation in step S7.
[0118]
Fourth, since the YC processing unit 5 converts the RAW data output from the first storage unit 4 into YC data for each small image, the scale of the circuit constituting the YC processing unit 5 can be reduced.
[0119]
(Embodiment 2)
The digital still camera according to Embodiment 2 of the present invention is different from the digital still camera according to Embodiment 1 in that a second storage unit is provided and YC data is recorded therein.
[0120]
Hereinafter, the digital still camera according to the second embodiment of the present invention will be described with reference to FIGS.
[0121]
First, the configuration of the digital still camera according to Embodiment 2 of the present invention will be described. FIG. 7 is a block diagram showing a configuration of a digital still camera according to Embodiment 2 of the present invention. Hereinafter, each component in FIG. 7 will be described.
[0122]
First, the second storage unit 33 records the YC data subjected to RAW / YC conversion by the YC processing unit 25 under the control of the control unit 22, and outputs the YC data to the compression conversion unit 28. Note that the second storage unit 33 is a memory such as a DRAM or an SRAM, and it is sufficient if it has a recording area capable of recording data corresponding to scanning lines more than twice the number of scanning lines to be compressed and converted at one time. Therefore, it is not necessary to have a large recording area unlike the first storage unit 24. For example, in the case of JPEG conversion, the second storage unit 33 only needs to have a recording area for 16 scanning lines. Thus, the fact that the recording area of the second storage unit 33 is small is sufficient because YC data is generated whenever necessary as will be described below, and therefore it is not necessary to hold the entire YC data. Because.
[0123]
Note that the circuit configuring the second storage unit 33 and the circuit configuring the control unit 22, the YC processing unit 25, and the compression conversion unit 28 may be configured to be configured on a single semiconductor chip. . By doing so, the power consumption of the second storage unit 33 can be reduced, and the writing speed of the YC data to the second storage unit 33 and the reading speed of the YC data from the second storage unit 33 are improved. Can be made. In addition, even if it is made to comprise the circuit which comprises the 2nd memory | storage part 33, and the circuit which comprises the control part 22, the YC process part 25, and the compression conversion part 28 on a single semiconductor chip as mentioned above, Since the recording area of the second storage unit 33 is small, the inclusion of the second storage unit 33 makes it particularly difficult to design this semiconductor chip or increases the manufacturing cost of this LSI. Such disadvantages do not occur.
[0124]
The operation unit 21 is a shutter button or the like. When the user operates the operation unit 21, the operation unit 21 instructs the control unit 22 to perform continuous shooting. The control unit 22 includes an imaging unit 23, a first storage unit 24, a YC processing unit 25, a level measurement unit 26, a coefficient setting unit 27, a compression conversion unit 28, a code amount measurement unit 29, a scale factor setting unit 30, The recording unit 31, the scratch correction calculation unit 32, and the second storage unit 33 are controlled.
[0125]
The imaging unit 23 includes an imaging element (not shown) such as a CCD, and converts an optical signal from an optical system part (not shown) into RGB three primary colors and converts the digitized electrical signal. When receiving an instruction from the control unit 22, the electrical signal is output to the first storage unit 24. The first storage unit 24 includes a DRAM or the like, and includes a RAW recording region 24a for recording the output of the imaging unit 23, that is, RAW data, and a compressed data recording region 24c for recording the output of the compression conversion unit 28. Further, under the control of the control unit 22, the data recorded in the RAW recording area 24a is output to the YC processing unit 25, and the data recorded in the compressed data recording area 24c is output to the recording unit 31, respectively.
[0126]
Further, the YC processing unit 25 acquires the RAW / YC conversion calculation coefficient from the coefficient setting unit 27 and the RAW data from the RAW recording area 24 a of the first storage unit 24 under the control of the control unit 22. Then, based on the calculation coefficient, the RAW data is converted into YC data. Further, the RAW data temporarily stored in the YC processing unit 25 in the conversion process is output to the defect correction calculation unit 32, and the converted YC data is output to the second storage unit 33.
[0127]
In addition, the defect correction calculation unit 32 corrects a defect in the RAW data under the control of the control unit 22, and outputs the corrected RAW data to the RAW recording area 24a. The level measuring unit 26 includes a counter or the like, and acquires the output of the imaging unit 23, that is, RAW data under the control of the control unit 22, and measures the level of the RAW data for each of the three primary colors of RBG.
[0128]
Also, the coefficient setting unit 27 calculates a calculation coefficient for RAW / YC conversion based on the measurement result of RAW data for one screen in the level measurement unit 26 under the control of the control unit 22, and temporarily stores the calculation coefficient therein. The calculation coefficient is output to the YC processing unit 25 as necessary. Further, the compression conversion unit 28 acquires the outputs of the second storage unit 33 and the scale factor setting unit 30 under the control of the control unit 22, and the second storage unit 33 based on the output of the scale factor setting unit 30. YC data is compressed and converted, and the compressed data, that is, compressed data is output to the compressed data recording area 24c and the code amount measuring unit 29.
[0129]
The code amount measuring unit 29 acquires compressed data from the compression conversion unit 28 under the control of the control unit 22 and measures the code amount of the compressed data, and includes a counter and the like. The scale factor measuring unit 10 calculates a scale factor based on the code amount for one screen measured by the code amount measuring unit 29, temporarily stores the scale factor therein, and a compression conversion unit as necessary. To 28.
[0130]
The recording unit 31 includes a flash memory or the like, acquires compressed data recorded in the compressed data recording area 24c under the control of the control unit 22, and records the compressed data.
[0131]
Next, an operation of recording image data for one screen of the digital still camera according to Embodiment 2 of the present invention will be described. FIG. 8 is a flowchart showing the operation of the control unit 22 when recording image data for one screen by the digital still camera according to Embodiment 2 of the present invention.
[0132]
First, an optical signal from an optical system part (not shown) is input to the imaging unit 23, and the imaging unit 23 is controlled to convert the optical signal into RAW data, and the RAW data is stored in the first storage. The output is made to the unit 24 and the level measuring unit 26 (step S21). Next, by controlling the first storage unit 24, the RAW data that is the output of the imaging unit 23 is acquired, recording in the RAW recording area 24a is started (step S22), and the level measuring unit 26 is controlled. By doing so, the RGB level measurement of the RAW data which is the output of the imaging unit 23 is started (step S23).
[0133]
Next, the first storage unit 24 is controlled to transmit information indicating the recording amount of the RAW data in the RAW recording area to the control unit 22 (step S24). At this time, if the amount of RAW data recorded exceeds 6 lines according to the information, the process proceeds to step S25, and until that time, the process waits in step S24.
[0134]
Next, in step S25, the first storage unit 24, the YC processing unit 25, the coefficient setting unit 27, the scratch correction calculation unit 32, and the second storage unit 33 are controlled to convert the RAW data into YC data. At the same time, defects in RAW data are corrected. At this time, the YC processing unit 25 acquires the raw data from the first storage unit 24 and the calculation coefficient from the coefficient setting unit 27, converts the raw data to YC data based on the calculation coefficient, and performs the second storage. The data is recorded in the unit 33. Further, the scratch correction calculation unit 32 acquires RAW data from the YC processing unit 25, corrects the defect of the RAW data, and outputs only the corrected portion of the RAW data to the first storage unit 24. The corrected RAW data is recorded in the RAW recording area 24a of the first storage unit 24.
[0135]
Next, in the YC processing monitoring step S26, when the YC processing unit 25 is monitored and RAW data for one macroblock that can be converted by the compression conversion unit 28 is RAW / YC converted, the process proceeds to step S27, and the first The storage unit 24, compression conversion unit 28, code amount measurement unit 29, scale factor setting unit 30 and second storage unit 33 are controlled to perform the following operations. First, the scale factor setting unit 30 outputs the scale factor, and the second storage unit 33 outputs the YC data. Next, based on the scale factor, the acquired YC data is compression converted by the compression conversion unit 28. Next, the compressed data obtained by the compression conversion is output to the code amount measuring unit 29, and the code amount measuring unit 29 is caused to measure the code amount, that is, the total number of bits of the compressed data.
[0136]
Next, in step S28, the level measuring unit 26 and the compression conversion unit 28 are controlled to monitor whether or not the compression conversion for one screen has been completed, and when completed, the process proceeds to step S29, and the coefficient setting unit 27 is set. Control is performed to obtain the total level for each RGB from the level measuring unit 26, and the calculation coefficient of the RAW / YC conversion is calculated based on the level, and the calculation coefficient is temporarily stored therein.
[0137]
Next, the code amount measuring unit 29 and the scale factor setting unit 30 are controlled so that the code amount for one screen is acquired from the code amount measuring unit 29, the scale factor is calculated based on the code amount, and the scale factor is calculated. Is temporarily stored inside (step S30). Next, the first storage unit 24, the YC processing unit 25, the coefficient setting unit 27, and the second storage unit 33 are controlled so that the RAW data is transmitted from the first storage unit 24 and the RAW / YC is transmitted from the coefficient setting unit 27. The conversion calculation coefficient is acquired, and the RAW data is converted into YC data based on the calculation coefficient, and is written in the second storage unit 33 (step S31).
[0138]
Next, in step S32, as in step S26, the YC processing unit 25 is monitored. When RAW data for one macroblock has been RAW / YC converted, the process proceeds to step S33, where the first storage unit 24, The compression conversion unit 28, the scale factor setting unit 30 and the second storage unit 33 are controlled to acquire YC data, compress the YC data, and record the compressed data after compression conversion in the compressed data recording area 24c. Let
[0139]
Finally, in step S34, the compression conversion unit 28 is monitored to detect whether the compression conversion of YC data for one screen and the writing of the compressed data after the compression conversion to the first storage unit 24 have been completed. When these are finished, the control by the control unit 22 for the image pickup operation for one screen is finished.
[0140]
The operation timing of the digital still camera according to Embodiment 2 of the present invention during continuous shooting is the same as the operation timing of the digital still camera according to Embodiment 1 shown in FIG. Omitted.
[0141]
As described above, according to the second embodiment of the present invention, the second storage unit 33 is provided, and the YC data is recorded in the second storage unit 33, thereby using the recording area of the first storage unit 24. The capacity can be reduced. In addition, the number of times that the YC processing unit 25 and the compression conversion unit 25 access the first storage unit 24 can be reduced, power consumption of the first storage unit 24 can be reduced, and the first It is possible to prevent the access to the storage unit 24 from being concentrated and the processing speed of the entire digital still camera from slowing down.
[0142]
Further, by configuring the circuit constituting the second storage unit 33 and the circuit constituting the control unit 22 on a single semiconductor chip, the power consumption of the second storage unit 33 can be reduced. The writing speed of YC data to the second storage section 33 and the reading speed of YC data from the second storage section 33 can be improved. As described above, it is sufficient that the capacity of the recording area of the second storage unit 33 is small. Therefore, when the semiconductor chip includes the second storage unit 33, the design becomes specially difficult or the manufacturing is performed. There is no demerit such as an increase in cost.
[0143]
(Embodiment 3)
The digital still camera according to Embodiment 3 of the present invention is different from the digital still camera according to Embodiment 1 of the present invention in that the setting is based on the distribution of YC data, not the level of RAW data.
[0144]
Hereinafter, a digital still camera according to Embodiment 3 of the present invention will be described with reference to FIGS. 3, 9, and 10, focusing on the above differences.
[0145]
First, the configuration of a digital still camera according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 9 is a block diagram showing a configuration of a digital still camera according to Embodiment 3 of the present invention. Hereinafter, each component in FIG. 9 will be described.
[0146]
First, the operation unit 41 is a shutter button or the like. When the user operates the operation unit 41, the operation unit 41 instructs the control unit 42 to perform continuous shooting. The control unit 42 includes an imaging unit 43, a first storage unit 44, a YC processing unit 45, a distribution measurement unit 46, a coefficient setting unit 47, a compression conversion unit 48, a code amount measurement unit 49, a scale factor setting unit 50, The recording unit 51 and the scratch correction calculation unit 52 are controlled. The imaging unit 43 includes an imaging element (not shown) such as a CCD, and converts an optical signal from an optical system part (not shown) into RGB three primary colors and converts it into a digitized electrical signal. When receiving an instruction from the control unit 42, the electrical signal is output to the first storage unit 44.
[0147]
The first storage unit 44 includes a DRAM or the like, and includes a RAW recording area 44a for recording the output of the imaging unit 43, that is, RAW data, a YC recording area 44b for recording the output of the YC processing unit 45, and the compression conversion unit 48. A compressed data recording area 44c for recording output is provided. Also, under the control of the control unit 42, the data recorded in the RAW recording area 44a is recorded in the YC processing unit 45, the data recorded in the YC recording area 44b is recorded in the compression converting unit 48, and the data recorded in the compressed data recording area 44c is recorded. The data are output to the unit 51, respectively.
[0148]
Further, the YC processing unit 45 acquires the RAW / YC conversion calculation coefficient from the coefficient setting unit 47 and the RAW data from the RAW recording area 44 a of the first storage unit 44 under the control of the control unit 42. Then, based on the calculation coefficient, the RAW data is converted into YC data. Further, the RAW data temporarily stored in the YC processing unit 45 during the conversion process is output to the defect correction calculation unit 52, and the converted YC data is output to the YC recording area 44b and the distribution measurement unit 46.
[0149]
In addition, the defect correction calculation unit 52 corrects a defect in the RAW data under the control of the control unit 42, and outputs the corrected RAW data to the RAW recording area 44a. The distribution measuring unit 46 includes a counter and the like, acquires the output of the YC processing unit 45, that is, YC data under the control of the control unit 42, and measures the distribution of the YC data. Also, the coefficient setting unit 47 calculates a calculation coefficient for RAW / YC conversion based on the distribution of YC data for one screen in the distribution measurement unit 46 under the control of the control unit 42, and temporarily stores the calculation coefficient therein. And the calculation coefficient is output to the YC processing unit 45 as necessary. Here, the calculation coefficient of the RAW / YC conversion is calculated by first determining a target distribution and then obtaining a deviation between the target distribution and the distribution of the YC data measured by the distribution measuring unit 46. .
[0150]
Further, the compression conversion unit 48 acquires the outputs of the YC recording area 44b and the scale factor setting unit 50 under the control of the control unit 42, and outputs the YC recording area 44b based on the output of the scale factor setting unit 50. The YC data is compressed and converted, and the data after the compression conversion, that is, the compressed data is output to the compressed data recording area 44 c and the code amount measuring unit 49.
[0151]
The code amount measuring unit 49 acquires compressed data from the compression conversion unit 48 under the control of the control unit 42 and measures the code amount of the compressed data, and includes a counter and the like. The scale factor measuring unit 10 calculates a scale factor based on the code amount for one screen measured by the code amount measuring unit 49, temporarily stores the scale factor therein, and a compression conversion unit as necessary. Output to 48. The recording unit 51 includes a flash memory or the like, acquires compressed data recorded in the compressed data recording area 44c under the control of the control unit 42, and records the compressed data.
[0152]
Next, an operation of recording image data for one screen of the digital still camera according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 10 is a flowchart showing the operation of the control unit 42 when recording image data for one screen by the digital still camera according to Embodiment 3 of the present invention.
[0153]
First, an optical signal from an optical system part (not shown) is input to the imaging unit 43, and the imaging unit 43 is controlled to convert the optical signal into RAW data, and the RAW data is stored in the first storage. The data is output to the unit 44 (step S41), and the first storage unit 44 is controlled to acquire RAW data, which is the output of the imaging unit 43, and start recording in the RAW recording area 44a (step S42).
[0154]
Next, the first storage unit 44 is controlled to transmit information indicating the recording amount of RAW data in the RAW recording area to the control unit 42 (step S44). At this time, if the amount of RAW data recorded exceeds 6 lines according to the information, the process proceeds to step S45, and until that time, the process waits in step S44. Next, the first storage unit 44, the YC processing unit 45, the coefficient setting unit 47, and the flaw correction calculation unit 52 are controlled to convert the RAW data into YC data, and at the same time, correct defects in the RAW data (step S45). ). At this time, the YC processing unit 45 causes the RAW data and the coefficient setting unit 47 to acquire the RAW data from the first storage unit 44, converts the RAW data to YC data based on the calculation coefficient, and performs the first storage. The data is recorded in the YC data recording area 4b of the unit 44. In addition, the scratch correction calculation unit 52 acquires RAW data from the YC processing unit 45, corrects defects in the RAW data, and outputs only the corrected portion of the RAW data to the first storage unit 44. The corrected RAW data is recorded in the RAW recording area 44 a of the first storage unit 44.
[0155]
Next, the distribution measurement unit 46 is controlled to start the distribution measurement of the YC data that is the output of the YC processing unit 45 (step S43). In step S46, the YC processing unit 45 is monitored and the compression conversion unit 48 is monitored. When the RAW data for one macroblock that can be converted in step RAW / YC has been converted, the process proceeds to step S47 to control the first storage unit 44, compression conversion unit 48, code amount measurement unit 49, and scale factor setting unit 50. Then, the following operation is performed. First, the scale factor setting unit 50 outputs the scale factor, and the first storage unit 44 outputs the YC data. Next, the acquired YC data is compressed and converted by the compression conversion unit 48 based on the scale factor. Next, the compressed data obtained by the compression conversion is output to the code amount measurement unit 49, and the code amount measurement unit 49 measures the code amount, that is, the total number of bits of the compressed data.
[0156]
Next, in step S48, the compression conversion unit 48 is controlled to monitor whether or not the compression conversion for one screen has been completed, and when completed, the process proceeds to step S49, and the distribution measurement unit 46 and coefficient setting unit 47 are detected. To obtain a distribution of YC data from the distribution measurement unit 46, calculate a calculation coefficient of RAW / YC conversion based on the distribution, and temporarily store the calculation coefficient inside.
[0157]
Next, the code amount measuring unit 49 and the scale factor setting unit 50 are controlled so that the code amount for one screen is acquired from the code amount measuring unit 49, the scale factor is calculated based on the code amount, and the scale factor is obtained. Is temporarily stored (step S50), and the first storage unit 44, the coefficient setting unit 47, and the YC processing unit 45 are controlled, and the RAW data is transferred from the first storage unit 44 to the coefficient setting unit 47. RAW / YC conversion calculation coefficients are respectively acquired, RAW data is converted into YC data based on the calculation coefficients, and written to the recording area 4a of the first storage unit 44 (step S51).
[0158]
Next, in step S52, as in step S46, the YC processing unit 45 is monitored. When RAW data for one macroblock has been RAW / YC converted, the process proceeds to step S53, where the first storage unit 44, The scale factor setting unit 50 and the compression conversion unit 48 are controlled to acquire YC data, compress the YC data, and record the compressed data after the compression conversion in the compressed data recording area 44c.
[0159]
Finally, in step S54, the compression conversion unit 48 is monitored to detect whether the compression conversion of YC data for one screen and the writing of the compressed data after the compression conversion to the first storage unit 44 have been completed. Then, when these are finished, the control by the control unit 42 for the imaging operation for one screen is finished.
[0160]
Next, the operation of the digital still camera according to Embodiment 3 of the present invention when continuous shooting is performed will be described below with reference to FIG. 3, FIG. 9, and FIG. The operation up to time B is the same as that of the digital still camera according to Embodiment 1, and the description thereof is omitted.
[0161]
Next, at time B, the process proceeds to step S42, and RAW data is written into the RAW recording area 44a (track a1 in FIG. 3). This is different from the operation of the digital still camera according to Embodiment 1 in that level measurement is not performed at this time. Next, at time C, in addition to the operation of the digital still camera according to the first embodiment, distribution measurement of YC data is started (step S43). Next, at time E, when the first reading of the RAW data (trajectory a2 in FIG. 3) is completed, the process proceeds to step S49 immediately after step S48. At this time, a calculation coefficient for RAW / YC conversion is set based on the distribution of YC data measured from time C to time E.
[0162]
Finally, after the time E, from the generation of the compressed data of the first screen to the generation and storage of the compressed data of the final screen, the operation after the time E is the same as the operation of the digital still camera according to the first embodiment. Since there is, explanation is omitted.
[0163]
In the second and subsequent screens of continuous shooting, the calculation coefficient used in step S51 for the immediately preceding input image is used as the calculation coefficient for RAW / YC conversion in step S45 (for example, the YC data indicated by locus b2 in FIG. 3). The calculation coefficient used in the generation of (1) may be used as a calculation coefficient for generating the YC data indicated by the locus b3 in FIG. As a result, the calculation coefficient of the RAW / YC conversion in step S51 of the previous input screen is optimized so that the converted image is not crushed or sunken, so that the current input image If there is no significant difference from the input image, it can be expected that the current input image is correctly converted into YC data. However, when the shooting interval is short, there is a high possibility that the current input image is not significantly different from the previous input image. Therefore, the calculation coefficient calculated from the previous input image may be reused without correction. Although good results can be expected, it may be safer to correct the calculation coefficient when the shooting interval is long. This is because if the input image is changed and the calculation coefficient corresponding to the immediately preceding input image is inappropriate, the converted image is crushed or darkened.
[0164]
Further, the YC processing unit 45 corrects the calculation coefficient calculated by the coefficient setting unit 47 so that the amplitude of the luminance signal or the color signal is suppressed, and obtains the calculation coefficient based on the corrected calculation coefficient. The RAW data converted by the imaging unit 3 corresponding to the input image next to the input image may be converted into YC data.
[0165]
The reason is as follows. The generation of YC data in step S45 is mainly intended to estimate the amount of codes, so even if the distribution of the generated YC data deviates from the desired distribution, there is no problem in itself. However, if the code amount obtained by compressing and converting the YC data generated in the YC processing / scratch correction start step S45 is significantly different from the code amount obtained by compressing and converting the correctly generated YC data, the target scale factor is controlled. Cannot be done correctly. If the calculation coefficient tends to excessively increase the amplitude of the YC data, the generated YC data is partially saturated at the maximum value and white crushing occurs. Compression conversion has the property of converting an image containing more high-frequency components into a code with a larger capacity, and in the saturated part, the high-frequency components of the image are lost by sticking the data to the maximum value, so when white crushing occurs The amount of code after compression conversion is greatly reduced. Once white crushing occurs, it is difficult to correctly control the scale factor because the amount of code when there is no white crushing cannot be estimated. On the other hand, if the calculation coefficient tends to excessively reduce the amplitude of the YC data, darkening occurs. Since the compression conversion has a property of converting an image having a small amplitude into a code having a smaller capacity, the amplitude of the YC data generated in step S45 is small and the amplitude of the YC data generated in step S51 is larger. Can correct the code amount estimate more than the code amount obtained by the compression conversion in step S47, and then optimize the scale factor used in the compression conversion in step S53. In this way, it is difficult to estimate the amount of code if the arithmetic coefficient enlarges the amplitude of the YC data too much, but when the arithmetic coefficient makes the amplitude of the YC data too small, the estimation of the amount of code is corrected. Therefore, when the calculation coefficient used for generating the YC data in step S45 is in the direction of increasing the amplitude of the YC data, it is safer to correct in the direction of decreasing the amplitude. Also, if the time interval from the last shooting is long, the subject may be brighter during that time, so it can be said that it is safer to correct the calculation coefficient in the direction of decreasing the amplitude. .
[0166]
As described above, according to the third embodiment of the present invention, the RAW data stored in the first storage unit 44 is converted into YC data by the YC processing unit 45 (step S45), and converted by the YC processing unit 5. The compressed YC data is converted into compressed data by the compression conversion unit 8 (step S47), and the calculation coefficient is calculated by the distribution measurement unit 46 and the coefficient setting unit 47 based on the YC data converted by the YC processing unit 45 (step S47). S49) After setting the scale factor in the scale factor setting unit 50 based on the compressed data converted by the compression conversion unit 48 (step S50), the first storage unit 44 stores the scale factor under the control of the control unit 42. RAW data is converted again to YC data by the YC processing unit 45 (step S51), and the YC data converted again by the YC conversion unit 5 is converted into a scale factor setting unit. By based on the scale factor that has been set at 0 is converted into compressed data compression conversion unit 8 (step S53), it controls the distribution of the YC data after RAW / YC conversion in step S51 with high accuracy. This is because, when optimizing calculation coefficients based on the distribution of RAW data, various nonlinear operations including clamping and clipping are performed in the process until RAW data is converted to YC data. According to the third embodiment of the present invention, the RAW / YC conversion is performed twice, but the distribution of the YC data after converting the RAW data into YC data is not necessarily optimized. This is because the calculation coefficient is corrected so that the deviation from the target distribution becomes zero.
[0167]
Further, the YC processing unit 45 starts to convert the RAW data stored in the first storage unit 44 into YC data within a period in which the first storage unit 44 stores the RAW data converted by the imaging unit 43. The time required for continuous shooting operation can be shortened.
[0168]
The YC processing unit 45 converts the RAW data corresponding to the next input image of the input image into YC data based on the calculation coefficient set by the coefficient setting unit 47 for the input image (step S49). By (step S45), YC data without white crushing can be obtained.
[0169]
Further, the YC processing unit 45 corrects the calculation coefficient calculated by the coefficient setting unit 47 so that the amplitude of the luminance signal or the color signal is suppressed, and obtains the calculation coefficient based on the corrected calculation coefficient. By converting the RAW data converted by the imaging unit 43 corresponding to the input image next to the input image into YC data, saturation and white-out of the maximum value of YC data can be prevented.
[0170]
(Embodiment 4)
The digital still camera according to Embodiment 4 of the present invention is different from the digital still camera according to Embodiment 1 in that the RAW data writing speed and reading speed are approximately the same. Hereinafter, a digital still camera according to the fourth embodiment of the present invention will be described with reference to FIGS. 1, 2, and 11 with the focus on this point.
[0171]
First, the configuration of the digital still camera according to Embodiment 4 of the present invention and the control flow of the control unit 2 when recording image data for one screen are shown in FIGS. 1 and 2, respectively. Since it is the same as that of form 1, description is abbreviate | omitted.
[0172]
Next, FIG. 11 which is a timing chart showing the operation of the digital still camera according to Embodiment 4 of the present invention when continuous shooting is performed will be described. In FIG. 11, the horizontal axis represents time. In addition, the time utilized when it demonstrates below is written as a time A, B, C, etc. on the horizontal axis.
[0173]
FIG. 11 (a) is a diagram showing the time change of the address for accessing the RAW data, the vertical axis shows the address of the RAW recording area 4a, and the upper and lower dotted lines in the figure indicate the upper limit and the lower limit of the address, respectively. The thick arrow lines a61, a64, and a67 indicate the locus of the write address of the RAW data, and the thin arrow lines a62, a63, a65a to c, a66, and a68a to c indicate the locus of the read address of the RAW data.
[0174]
FIG. 11B is a diagram showing the time change of the recording state of YC data. The upper and lower dotted lines in the drawing indicate the recording state and the non-recording state, respectively, and the solid line indicates the locus of the recording state. , B61 is the first RAW / YC conversion of the first screen, b62 is the second of the first screen, b63 is the first of the second screen, b64 is the second of the second screen, and b65 is the first RAW / YC conversion of the third screen. The subsequent YC data is shown respectively.
[0175]
Further, FIG. 11C is a diagram showing a temporal change in the operation state of the scratch correction calculation unit 12, in which the upper and lower dotted lines indicate the correction processing state and the non-correction processing state, respectively, and the solid line indicates the correction processing. The locus of the state is shown. Further, FIG. 11D is a diagram showing the time change of the recording state of the compressed data, where the upper and lower dotted lines indicate the recording state and the non-recording state, respectively, and the solid line indicates the locus of the recording state. .
[0176]
Next, the operation of the digital still camera according to Embodiment 4 of the present invention when continuous shooting is performed will be described below with reference to FIG. 1, FIG. 2, and FIG. First, in FIG. 11, the continuous shooting operation is started at time A, and the operation up to time E is the same as the operation of the digital still camera according to the first embodiment, and thus description thereof is omitted.
[0177]
Next, at time E, when the first reading of the RAW data (trajectory a62 in FIG. 11) is completed, immediately after that, the process proceeds to Step S11 through Step S8, Step S9 and Step S10 in FIG. Reading from the RAW recording area 4a (trajectory a63 in FIG. 11), RAW data is converted into YC data and recorded in the YC recording area 4b (trajectory b62 in FIG. 11).
[0178]
Here, the gradients of the trajectories a62, a63, a65a to c, a66, and a68a to c are all the same as those of the trajectories a61, a64, and a67. That is, the RAW data writing speed and reading speed are approximately the same.
[0179]
Next, at time F, the process proceeds to step S13, and compressed data is generated and recorded in the compressed data recording area 4c.
[0180]
Next, from time D to time G, in the same manner as in the digital still camera according to the first embodiment, for the second screen, the optical signal is converted to RAW data in step S1, and the RAW data is written at time G. (Track a64 in FIG. 11) is started.
[0181]
Next, generation of the second YC data of the first screen is completed at time J (trajectory b62 in FIG. 11), and recording of the compressed data of the first screen in the compressed data recording area 4c is completed at time K. Then, at time J, the first RAW / YC conversion on the second screen is started (trajectory b63 in FIG. 11), and RAW data is read for this purpose (trajectories a65a to c in FIG. 11).
[0182]
Here, in the reading of the RAW data indicated by the trajectories a65a to c in FIG. 11, by repeating the process of advancing the reading address by 56 lines when 72 lines are read, the reading amount of the RAW data is nearly halved. Reduce. By thinning out and reading out RAW data in this way, it is possible to reduce the processing time for code amount estimation to nearly half. If all addresses are read without thinning out, the RAW data for the third screen cannot be written until the reading of the RAW data for the second screen is completed, and the continuous shooting speed is reduced.
[0183]
Next, in RAW / YC conversion, 64 lines of YC data are generated from 72 lines of RAW data. Then, using the generated YC data, the code amount is estimated by performing compression conversion in step S7 from time K to time M.
[0184]
Note that thinning is performed at a relatively long cycle of 128 lines because YC data generated for RAW data is reduced by 8 lines in order to perform vertical filtering in RAW / YC conversion. This is because when thinning is performed, the amount of YC data generated is extremely small compared to the amount of RAW data to be read. In addition, since compression conversion is processed in units of macroblocks having a height of 8 pixels, there is no waste if the read amount of RAW data is determined so that YC data generated in one cycle of thinning is a multiple of 8 lines.
[0185]
Hereinafter, for the second and subsequent screens, the first RAW / YC conversion creates YC data by thinning out RAW data. The operation after the second screen is the same as the operation of the first screen except for the method of reading out RAW data at the first generation of YC data. Further, the above-described operation is repeated, and the continuous shooting operation ends when imaging of a predetermined number of screens is completed.
[0186]
As described above, according to the fourth embodiment of the present invention, the YC processing unit 5 converts a part of the RAW data (the trajectories b63 and b65 in FIG. 11) stored in the first storage unit 4 into YC data. (Step S5), the compression converting unit 8 converts the YC data converted by the YC processing unit 5 into compressed data (Step S7), and the scale factor setting unit 10 is based on the compressed data converted by the compression converting unit 8. By setting the scale factor (step S10), the processing time for the RAW / YC conversion in step 5 and the code amount estimation in step 7 can be shortened, so that the processing speed per pixel of the RAW / YC conversion and compression conversion can be reduced to RAW data. It is possible to reduce the operation time required for imaging during continuous shooting while maintaining the same input speed as the above.
[0187]
Furthermore, since the processing speed per pixel of RAW / YC conversion and compression conversion and the input speed of RAW data are comparable, the entire signal processing circuit can be operated with the same clock, so that circuit design is facilitated.
[0188]
However, as a trade-off between the processing speed per pixel of RAW / YC conversion and compression conversion and the input speed of RAW data, there is no room for processing the entire screen to estimate the code amount, and it is necessary to perform thinning. Come. If thinning is performed at the code amount estimation stage, the accuracy of code amount control is slightly worse than that of the digital still camera according to Embodiment 1 that does not perform thinning. The code amount can be controlled with much higher accuracy than when the scale factor is used.
[0189]
【The invention's effect】
As described above, according to the present invention, it is possible to obtain an image that is comparable to an image that can be obtained with a conventional digital still camera, and in addition, it is possible to reduce the operation time required for continuous shooting. An excellent effect is obtained.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a digital still camera according to Embodiments 1 and 4 of the present invention.
FIG. 2 is a flowchart for explaining the operation of the digital still camera according to Embodiments 1 and 4 of the present invention.
FIG. 3 is a timing chart for explaining operations of the digital still camera according to Embodiment 1 of the present invention;
FIG. 4 is a block diagram showing a configuration of a YC processing unit and a flaw correction calculation unit of the digital still camera according to Embodiment 1 of the present invention.
FIG. 5 is a schematic diagram illustrating a pixel configuration for explaining a defect correction operation of the digital still camera according to Embodiment 1 of the present invention.
FIG. 6 is a schematic diagram showing a configuration of a YC recording area of the digital still camera according to Embodiment 1 of the present invention.
FIG. 7 is a block diagram showing a configuration of a digital still camera according to Embodiment 2 of the present invention.
FIG. 8 is a flowchart for explaining the operation of the digital still camera according to Embodiment 2 of the present invention;
FIG. 9 is a block diagram showing a configuration of a digital still camera according to Embodiment 3 of the present invention.
FIG. 10 is a flowchart for explaining the operation of the digital still camera according to Embodiment 2 of the present invention;
FIG. 11 is a timing chart for explaining the operation of the digital still camera according to Embodiment 4 of the present invention;
FIG. 12 is a block diagram showing a configuration of a conventional digital still camera.
FIG. 13 is a flowchart for explaining the operation of a conventional digital still camera.
FIG. 14 is a timing chart for explaining the operation of a conventional digital still camera.
FIG. 15 is a schematic diagram illustrating a storage state of a storage unit of a conventional digital still camera.
FIG. 16 is a block diagram illustrating a configuration of a YC processing unit and a defect correction calculation unit of a conventional digital still camera.
[Explanation of symbols]
2, 22, 42 Control unit
3, 23, 43 Imaging unit
4, 24, 44 First storage unit
5, 25, 45 YC processing unit
6, 26 Level measurement unit
7, 27, 47 Coefficient setting part
8, 28, 48 Compression converter
9, 29, 49 Code amount measurement unit
10, 30, 50 Scale factor setting section
11, 31, 51 Recording unit
33 Second storage unit
46 Distribution measurement unit

Claims (10)

An imaging unit that converts an optical signal indicating an input image into RAW data;
A YC processing unit for converting the RAW data into YC data;
A compression conversion unit that converts the YC data converted by the YC processing unit into compressed data;
A compression coefficient setting unit that performs code amount estimation by calculating a compression coefficient based on the compressed data converted by the compression conversion unit;
A storage unit that stores RAW data generated by the imaging unit and stores YC data corresponding to the stored RAW data in a storage area different from the RAW data ;
The RAW data stored in the storage unit when the compression coefficient setting unit calculates the compression coefficient by causing the compression coefficient setting unit to perform code amount estimation overlapping with the RAW data writing operation to the storage unit. The YC processing unit is controlled so as to be read again and converted into YC data, and the YC data converted again by the YC processing unit is converted again into compressed data based on the compression coefficient calculated by the compression coefficient setting unit. A control unit for controlling the compression conversion unit;
A digital still camera comprising: An imaging unit that converts an optical signal indicating an input image into RAW data;
A YC processing unit for converting the RAW data into YC data;
A compression conversion unit that converts the YC data converted by the YC processing unit into compressed data;
A compression coefficient setting unit that performs code amount estimation by calculating a compression coefficient based on the compressed data converted by the compression conversion unit;
A first storage unit that stores RAW data generated by the imaging unit ;
A second storage unit for storing YC data corresponding to the stored RAW data in a storage area different from the RAW data ;
When the code amount estimation is performed by the compression coefficient setting unit in overlap with the operation of writing the RAW data to the first storage unit, and the compression coefficient setting unit calculates the compression coefficient, the first storage unit The YC processing unit is controlled to read out the stored RAW data and convert it to YC data again, and the YC data converted again by the YC processing unit is based on the compression coefficient calculated by the compression coefficient setting unit. A control unit that controls the compression conversion unit so as to convert it into compressed data again;
A digital still camera comprising: Circuit and the control unit constituting the second storage unit, the circuit constituting the YC processing unit and the compression conversion unit according to claim 2, characterized in that it is constructed on a single semiconductor chip Digital still camera. An imaging unit that converts an optical signal indicating an input image into RAW data composed of a plurality of color signals;
A calculation coefficient setting unit that calculates a calculation coefficient used when YC data is generated by mixing a plurality of color signals of the RAW data ;
A YC processing unit for converting the RAW data into YC data based on the calculated calculation coefficient;
A compression conversion unit that converts the YC data converted by the YC processing unit into compressed data;
A compression coefficient setting unit that performs code amount estimation by calculating a compression coefficient based on the compressed data converted by the compression conversion unit;
A storage unit that stores RAW data generated by the imaging unit and stores YC data corresponding to the stored RAW data in a storage area different from the RAW data ;
RAW data stored in the storage unit when the compression coefficient setting unit calculates a compression coefficient by causing the compression coefficient setting unit to perform code amount estimation overlapping with the RAW data writing operation to the storage unit The YC processing unit is controlled so as to be converted again into YC data based on the calculation coefficient set by the calculation coefficient setting unit, and the YC data converted again by the YC processing unit is converted by the compression coefficient setting unit. A control unit that controls the compression conversion unit to convert the compressed data again based on the calculated compression coefficient;
A digital still camera comprising: The YC processing unit, based on the calculation coefficient set by the calculation coefficient setting section to the input image, and converting the RAW data corresponding to the next input image of the input image to the YC data The digital still camera according to claim 4. The YC processing unit corrects the calculation coefficient calculated by the calculation coefficient setting unit so that the amplitude of the luminance signal or the color signal is suppressed, and based on the corrected calculation coefficient, the next input of the input image The digital still camera according to claim 4, wherein RAW data converted by an imaging unit corresponding to an image is converted into YC data. Within the time the storage part or the first storage unit stores the converted RAW data was by the imaging unit, the YC processing section, the RAW data stored in the storage part or the first storage unit 7. The digital still camera according to claim 1, wherein conversion into YC data is started. A scratch correction calculation unit for correcting defects in RAW data,
The YC processing unit has a line memory for temporarily storing a part of RAW data,
8. The digital still camera according to claim 1, wherein the scratch correction calculation unit reads out RAW data stored in the line memory and sequentially corrects defects in the read out RAW data. . The storage part or the first storage unit is divided outputs the RAW data representing the input image into a plurality of small images, the small the YC processing unit, which is output from the storage part or the first storage unit 9. The digital still camera according to claim 1, wherein RAW data for each image is converted into YC data. The YC processing unit converts a part of the RAW data stored in the storage unit or the first storage unit into YC data, and the compression conversion unit converts the YC data converted by the YC processing unit into compressed data. The digital still camera according to claim 1, wherein the compression coefficient setting unit sets a compression coefficient based on the compressed data converted by the compression conversion unit.

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