JP5665282B2 - Imaging apparatus and control method thereof - Google Patents

Description

The present invention relates to an imaging apparatus and a control method thereof, a shading that is independent of the shading and the horizontal transfer position which depends on the horizontal transfer position about the Hare IMAGING DEVICE AND ITS CONTROL METHOD row.

  2. Description of the Related Art Conventionally, imaging apparatuses such as a digital camera and a digital video camera that record a photographed image using a CCD (Charge Coupled Device) or a CMOS APS (CMOS Active Pixel Sensor) as an imaging element have been put on the market. In these image pickup apparatuses, high image quality is provided by correcting shading in the dark and light of the image sensor. FIG. 11 shows a schematic configuration of an image sensor that is a constituent element of a conventional imaging device.

  In FIG. 11, reference numeral 1101 denotes a pixel portion in which pixels that photoelectrically convert light into electric signals are arranged in the vertical direction and the horizontal direction. Reference numeral 1102 denotes a row selection circuit (vertical direction selection circuit), and 1103 denotes a column readout circuit for reading out pixel signals. Reference numeral 1104 denotes a column memory, in which signals read by the column readout circuit 1103 are accumulated. The column memory 1104 is scanned by the column selection circuit 1105, and signals are taken out to the output line 1106 in order.

  FIG. 12 is a diagram illustrating an example of a read timing of a signal read from the image sensor of FIG.

  In FIG. 12, during the HBLK period, the signals of the pixels in the n rows selected by the row selection circuit 1102 are accumulated in the column memory 1104 by the column readout circuit 1103 in accordance with a plurality of clock signals (not shown). Thereafter, in the horizontal transfer period, the signal of the column memory 104 is scanned by the column selection circuit 1105 and sequentially output via the output line 1106. When the n-th horizontal transfer period is completed, the (n + 1) th row is selected next, and similarly, driving is performed in the HBLK period and the horizontal transfer period. Similarly, the HBLK period and the horizontal transfer period are repeated until one screen is read.

  By the way, the image sensor has shading in the vertical direction and the horizontal direction due to pixel non-uniformity. In particular, in the horizontal direction, there is shading in the horizontal direction depending on the non-uniformity of the readout circuit and the memory or the distance from the memory until the signal is output via the output line. These shadings are made uniform by correcting a signal output from the image sensor by a correction process of the image pickup apparatus, thereby providing high image quality. An outline of correction of shading will be described with reference to FIGS. 13 (a) and 13 (b).

  FIG. 13A shows the shape of the shading in the horizontal direction. As described above, the image sensor has different levels of gain and offset depending on the horizontal transfer position, which is shading. Shading correction is performed to correct this shading. Specifically, FIG. 13B shows the shading correction data superimposed on the image data at the time of shooting. By performing the subtraction or division from FIG. 13B to FIG. 13A, the influence of shading is reduced.

  The shading correction data for correcting shading is obtained from an image obtained before photographing. For example, in shading in the dark, an image is shot in a light-shielded state before shooting, shading correction data is obtained from the image, and shading is corrected by subtracting from the shot image. The shading correction data may be acquired when the imaging device is turned on or after an instruction to start shooting is issued.In that case, the time until the power is turned on becomes longer, or the time lag from the instruction to start shooting to the shooting is increased. It gets bigger. Therefore, it is most preferable to have the shading correction data in the memory before shipping the photographing apparatus.

  By the way, as one of the techniques for reading an image at high speed, there is an imaging device that performs the HBLK period and the horizontal transfer period at the same time (see, for example, Patent Documents 1 and 2).

  Further, in a moving image mode that exists as one of the functions of a recent digital camera or the like, the influence of the driving pulse in the HBLK period cannot be corrected by the above-described shading correction. The moving image mode includes thinning reading in which pixels are thinned and read out in order to increase the frame rate of the image sensor, and crop reading in which pixels are read out from the beginning of horizontal transfer. The shading in these moving image modes is shown in FIGS. 14 (a) to 14 (e).

  FIG. 14A is a diagram showing a shading shape when all pixels are read, and FIG. 14B is a diagram showing a shading shape when thinning is performed.

  FIG. 14C shows shading correction data obtained by thinning out the shading shape shown in FIG. With the shading correction data in FIG. 14C, the shading in FIG. 14B cannot be corrected. This is because the component depending on the horizontal transfer position in the shading shape can be corrected by the thinned data, but the shading shape due to the influence of the drive pulse during the HBLK period does not depend on the horizontal transfer position. In other words, if the shading correction data shown in FIG. 14C obtained by simply thinning out the shading correction data shown in FIG. 14A is corrected, the shading shape due to the influence of the drive pulse during the HBLK period is erroneously corrected. Resulting in.

  Similarly, FIG. 14D shows a shading shape when crop reading is performed, and FIG. 14E shows shading correction data for correcting shading of FIG. 14A for the number of pixels skipped by crop reading. The shading correction data is simply lost. Again, since the shading shape of FIG. 14D is different from the shape of the shading correction data of FIG. 14E, the shading shape of FIG. 14A is simply skipped by the number of pixels skipped by cropping. The shading correction data cannot be corrected.

JP 2001-45375 A Japanese Patent Laid-Open No. 2001-45378

  However, as described above, in the method in which the HBLK period and the horizontal transfer period are performed at the same time, shading due to the influence of the HBLK period does not depend on the horizontal transfer position, and thus shading correction data when the entire screen is read cannot be used. In order to avoid this problem, it is possible to have shading correction data corresponding to the number of crops in the moving image mode and the thinning rate, but a huge amount of memory is required to store the correction data.

  Even if the HBLK period and the horizontal transfer period are not performed at the same time, the same applies when the power supply voltage of the reading circuit fluctuates due to the drive pulse of the HBLK period and does not converge even in the horizontal transfer period. I can say that. That is, shading generated according to the horizontal transfer position depends on the horizontal transfer position, and shading due to power fluctuations received from the driving pulse in the HBLK period does not depend on the horizontal transfer position. In order to avoid this problem, it is possible to have shading correction data corresponding to the number of crops in the moving image mode and the thinning rate, but a large amount of memory for storing correction data is required.

The present invention has been made in view of the above problems, as many it is not necessary to prepare a memory corresponding to the number of modes, such as thinning and cropping, shading correction appropriate imaging device and capable of performing An object is to provide a control method thereof.

In order to achieve the above object, in the imaging apparatus according to claim 1, pixels that photoelectrically convert light into electric signals are arranged in vertical and horizontal directions, and signals from the pixels are vertically and horizontally transmitted by a plurality of drive pulses. An image sensor that transfers and outputs an image sensor that starts the horizontal blanking period of the (n + 1) th row during the horizontal transfer period of the nth row, and a horizontal transfer for an image signal output from the image sensor Correction means for performing first shading correction for correcting shading dependent on position, second shading correction for correcting shading independent of horizontal transfer position, and for performing the first shading correction A first shading correction value for each column of the image sensor and a second shading correction value for performing the second shading correction. Storage means for respectively storing, and having a.

In order to achieve the above object, according to a control method of an imaging apparatus according to claim 9, pixels that photoelectrically convert light into an electric signal are arranged in a vertical and horizontal direction, and signals from the pixel are vertically and horizontally converted by a plurality of drive pulses. An image pickup device for transferring in the horizontal direction and outputting the image pickup device, wherein the image pickup device has an image pickup device for starting a horizontal blanking period of the (n + 1) th row during the horizontal transfer period of the nth row. The first shading correction value for each column of the image sensor for correcting shading dependent on the horizontal transfer position and the first shading for correcting shading independent of the horizontal transfer position for the image signal output from And a correction step of performing shading correction based on the two shading correction values.

  According to the present invention, in an imaging apparatus having shading that depends on the horizontal transfer position and shading that does not depend on the horizontal transfer position, it is not necessary to prepare as many memories as the number of modes such as thinning and cropping, and shading correction can be performed. It can be done appropriately.

1 is a diagram illustrating a schematic configuration of an imaging element that is a component of an imaging apparatus according to a first embodiment of the present invention. It is a figure which shows an example of the read-out timing of the signal read from the image pick-up element of FIG. (A) is a figure which shows the shading shape at the time of driving an image pick-up element at the read-out timing shown in FIG. 2, (b) is a figure which shows the drive pulse in a HBLK period. (A) is a figure which shows the shading shape at the time of driving an image pick-up element at the read-out timing shown in FIG. 2, (b) is a figure which shows the drive pulse in a HBLK period, (c) is independent of a horizontal transfer position. The figure which shows a shading shape, (d) is a figure which shows the correction data which has the shading shape which thinned out the shading shape depending on the horizontal transfer position shown in FIG.4 (b), (e) is the correction data of FIG.4 (d). FIG. 4F is a diagram showing shading components removed from a photographed image, and FIG. 4F is correction data obtained by skipping the beginning of the shading shape depending on the horizontal transfer position shown in FIG. 4B by the number of pixels skipped by the crop. (G) is a figure which shows the shading component removed from a picked-up image by the correction data of FIG.4 (f). (A) is a diagram showing a flow of shading correction based on correction data 1 and 2, and (b) is a diagram showing a flow of shading correction based on correction data 1, 2 and 3. (C) is a diagram showing a flow of shading correction based on correction data 1, 2, and 4. (d) is a diagram showing a flow of shading correction based on correction data 1 to 4. It is a figure which shows schematic structure of the image pick-up element of FIG. 1 containing a clock terminal. It is a figure which shows the shape of the shading by the shake from the clock A in three reading positions. It is a block diagram which shows schematic structure of the imaging device which concerns on the 2nd Embodiment of this invention. 10 is a flowchart showing a flow of shading correction executed by an image signal processing circuit 1006 in FIG. 9. It is a figure which shows schematic structure of the image pick-up element which is a component of the conventional imaging device. It is a figure which shows an example of the read-out timing of the signal read from the image pick-up element of FIG. (A) is a figure which shows the shape of the shading of a horizontal direction, (b) is a figure which shows the shading correction data being superimposed on the image data at the time of imaging | photography. (A) is a figure which shows the shading shape at the time of all pixel reading, FIG.14 (b) is a figure which shows the shading shape at the time of performing thinning.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a diagram illustrating a schematic configuration of an imaging element that is a component of the imaging apparatus according to the first embodiment of the present invention.

  In FIG. 1, reference numeral 101 denotes a pixel portion in which pixels that photoelectrically convert light into electrical signals are arranged in the vertical direction and the horizontal direction. Reference numeral 102 denotes a row selection circuit (vertical selection circuit), and reference numeral 103 denotes a column readout circuit that reads out pixel signals. A column memory (first memory) 104 stores electrical signals read by the column readout circuit 103. Reference numeral 107 denotes a column memory 2 (second memory). Signals read from the pixels in the row selected by the row selection circuit 102 are alternately transferred to the column memory 104 and the column memory 2_107. The column memory 104 and the column memory 2_107 are scanned by the column selection circuit 105 (output circuit), and a signal is extracted to the output line 106.

  FIG. 2 is a diagram illustrating an example of a read timing of a signal read from the image sensor in FIG.

  In FIG. 2, in the HBLK1 period, the pixel signal of the nth row selected by the row selection circuit 102 is read out by the readout circuit 103 and stored in the column memory 104. In the HBLK2 period, similarly to the rows, the signals of the pixels in the (n + 1) th row selected by the row selection circuit 102 are read out by the readout circuit 103 and accumulated in the column memory 2_107.

  In the horizontal transfer period, the signals of the column memory 104 and the column memory 2_107 are scanned by the column selection circuit 105 and sequentially output via the output line 106. Since the imaging device includes the column memory 2_107 as the second memory, the horizontal transfer of the column memory 104 is performed while the signal is accumulated in the column memory 2_107 during the HBLK period (vertical transfer period). The column memory 104 can be overwritten during the transfer period. Similarly, the horizontal transfer of the column memory 2_107 is performed while a signal is accumulated in the column memory 104 during the HBLK period, and the column memory 2_107 can be overwritten during the horizontal transfer period of the column memory 104. Thus, in this embodiment, the HBLK period and the horizontal transfer period are performed at the same time (first reading method).

  Similarly, the n + 2 row HBLK1 period can be started in the (n + 1) th row horizontal transfer period, and the HBLK1 period or the HBLK2 period at the same time in the horizontal transfer period and the horizontal transfer period until one screen is read. Repeated. By adopting such a configuration, the period required for image reading is shortened by the HBLK period × the number of read rows, and high-speed reading is possible. An image sensor having an AD for each column can also increase the speed by holding the digital signal.

  Next, correction data will be described in terms of shading when the image sensor is driven at the readout timing shown in FIG.

  FIG. 3A is a diagram illustrating a shading shape when the imaging element is driven at the readout timing illustrated in FIG. 2, and FIG. 3B is a diagram illustrating drive pulses during the HBLK period.

  The influence due to the fluctuation of the driving pulse during the HBLK period is superimposed as shading. This is because the power supply voltage of the column readout circuit 103 and the signal line voltage fluctuate due to the drive pulse during the HBLK period, and the shading generated thereby is superimposed on the shading dependent on the horizontal transfer position. . The shading in which the influence of the drive pulse in the HBLK period is superimposed can be basically reduced by shading correction described later.

  FIG. 4A is a diagram showing a shading shape when the image sensor is driven at the readout timing shown in FIG. 2, as in FIG. FIG. 4B is a diagram showing a shading shape depending on the horizontal transfer position, and FIG. 4C is a diagram showing a shading shape independent of the horizontal transfer position due to the influence of the drive pulse in the HBLK period.

  The shading correction data having the same shape as that in FIG. 4B, which is a shading shape depending on the horizontal transfer position, is defined as correction data 1 (first shading correction value). The same shape shading correction data as in FIG. 4C, which is a shading shape that does not depend on the horizontal transfer position, is referred to as correction data 2 (second shading correction value).

  In order to obtain the correction data 1 and the correction data 2 from the shading shape of FIG. 4A, first, low-pass processing is performed on the shading data of the captured image having the shading shape of FIG. . As a result, an image having the shading shape shown in FIG. 4B is acquired to obtain correction data 1 (first shading correction). This means that the correction data 1 which is a low frequency component excluding a specific high frequency component is obtained. Further, by obtaining the difference of the shading shape of the correction data 1 from the shading data of the photographed image, an image having the shading shape of FIG. 4C is obtained to obtain correction data 2 (second shading correction). This means that correction data 2 that is a specific frequency component is obtained. As a result, among the data for generating the correction value at the time of driving in the full screen mode (first readout mode), the correction data 1 and the correction data 2 are respectively specified according to the data of a specific frequency component or a specific amplitude. Data of a specific amplitude can be obtained.

  As another method, the image sensor of FIG. 1 is driven by a driving method in which the horizontal transfer period and the HBLK period are not at the same time as shown in FIG. 12 (second reading method). First, an image having a shading component depending on the horizontal transfer position in FIG. 4B is acquired, and correction data 1 is created therefrom.

  Next, by driving as shown in FIG. 2, an image having the shading shape of FIG. 4A is acquired, and similarly, the shading difference of FIG. 4B is obtained from the shading shape of FIG. . Thereby, the correction data 2 having the shading shape of FIG. The correction data 1 and the correction data 2 obtained as described above are stored in a storage means (not shown).

  As for the shading correction method, in the case of full-screen reading (full-screen mode), the correction data 1 and the correction data 2 are subtracted or divided from the image data acquired by the image sensor, as shown in FIG. The shading shape can be corrected. In addition to simple addition / subtraction and division, addition / subtraction or division can be performed after the correction data 1 or the correction data 2 is multiplied by a coefficient (multiplication). The coefficient can be appropriately changed according to the driving conditions of the image sensor such as temperature, readout gain, output level, power supply voltage, and current value flowing through the column circuit.

  Next, correction in the full screen mode, correction in the thinning mode in which the number of horizontal transfer pixels is different from the full screen mode, and correction in the cropping will be described.

  Correction in the full screen mode (first readout mode) will be described with reference to FIGS. 4A to 4G and FIG.

  As described above, the shading correction data that depends on the horizontal transfer position is the correction data 1, and the shading correction data that does not depend on the horizontal transfer position is the correction data 2, which correspond to the shapes of FIGS. 4B and 4C, respectively. .

  In FIG. 5A, the correction data 1 is subtracted or divided from the photographed image. Thereby, the shading components shown in FIG. 4B included in the photographed image are removed. Next, the correction data 2 is subtracted or divided from the photographed image. Thereby, the shading component shown in FIG. 4C included in the photographed image is removed, and recording image data is acquired. The correction data 1 or the correction data 2 can be appropriately multiplied by a coefficient to be changed according to conditions such as temperature, readout gain, output level, power supply voltage, and current value flowing through the column circuit depending on the driving conditions of the image sensor. .

  The correction in the thinning mode will be described with reference to FIGS. 4 (a) to 4 (g) and FIG. 5 (b). Here, the description will be made using the thinning mode, but it is also effective in a method of thinning the number of pixels in the addition mode or the like.

  FIG. 4D shows correction data having a shading shape obtained by thinning out the shading shape depending on the horizontal transfer position shown in FIG.

  In FIG. 5B, the correction data 1 is converted into the correction data 3 according to the parameter X (first parameter) which is the horizontal transfer position information set by the mode. The shading correction data described in FIG. 4D is correction data 3 (third shading correction value). The parameter X is determined by the thinning rate. By subtracting or dividing the correction data 3 and the correction data 2 from the photographed image data, the shading component shown in FIG. 4E included in the photographed image is removed and recording image data is obtained. In addition, the correction data 3 or the correction data 2 is appropriately multiplied by a coefficient to be changed according to conditions such as temperature, readout gain, output level, power supply voltage, and current value flowing through the column circuit according to the driving conditions of the image sensor. Is possible. Further, the correction data 2 can be multiplied by a predetermined gain corresponding to the positional relationship described later. In addition, in the addition mode in which the number of pixels is thinned out, the parameter X is determined according to the number of pixels grouped by horizontal addition.

  Next, correction in the crop mode will be described.

  FIG. 4F shows correction data obtained by skipping the beginning of the shading shape depending on the horizontal transfer position shown in FIG. 4B by the number of pixels skipped by the crop.

  In FIG. 5B, the correction data 1 is converted into the correction data 3 according to the parameter X which is the horizontal transfer position information set by the mode. The shading correction data described with reference to FIG. The parameter X is determined by the number of pixels skipped by the crop. By subtracting or dividing the correction data 3 and the correction data 2 from the photographed image data, the shading component shown in FIG. 4G included in the photographed image is removed, and recording image data is obtained. In addition, the correction data 3 or the correction data 2 is appropriately multiplied by a coefficient to be changed according to conditions such as temperature, readout gain, output level, power supply voltage, and current value flowing through the column circuit according to the driving conditions of the image sensor. Is possible. Further, the correction data 2 can be multiplied by a predetermined gain corresponding to the positional relationship described later.

  In addition, there is a read mode in which the positional relationship between the horizontal transfer position and the drive pulse in the HBLK period is different from that in the full screen mode by changing the horizontal transfer frequency and the HBLK period. In the correction in that case, as shown in FIG. 6 (c), the correction data 2 (the fourth parameter) according to the horizontal transfer position from the parameter T (second parameter), which is the parameter of the time during the HBLK period. It is also possible to take the difference. The parameter T is determined from the horizontal transfer frequency and the pulse position of the drive pulse during the HBLK period. When changing the horizontal transfer frequency and the HBLK period at the time of moving images such as thinning and cropping as described above, the correction data 1 and the correction data 2 are converted into the correction data 3 and the correction data 4 respectively as shown in FIG. To correct. This makes it possible to correct shading included in the captured image.

  By the way, it is conceivable that shading caused by HBLK is not superimposed to the same extent at any horizontal transfer position depending on the image pickup device and is location dependent.

  FIG. 7 is a diagram illustrating a schematic configuration of the image sensor of FIG. 1 including a clock terminal.

  In FIG. 7, a clock A is supplied to the column readout circuit 103 from the outside via a clock buffer. It is conceivable that the fluctuation of the power source by the clock buffer changes depending on the horizontal transfer position.

  FIG. 8 is a diagram showing the shape of shading caused by shaking from the clock A at the three readout positions of the horizontal transfer position.

  When the degree of shading changes in proportion to the distance to the clock buffer, the gain (coefficient) indicated by the linear curve is multiplied by the reading position from the clock buffer from the shading data at the reading position of the two horizontal transfer positions. . As a result, it is not necessary to have data for each reading position of the horizontal transfer position. Here, the method for obtaining the coefficient by the linear curve from the reading position of the two horizontal transfer positions is described, but this is not the only case, and the coefficient may be obtained by the data of the primary or several-order curve from the plural reading positions at the horizontal transfer position. Good. Alternatively, the clock A may be generated internally without being supplied to the reading circuit via the clock buffer from the outside.

  As described above, the shading correction data is separated and stored into shading correction data that depends on the horizontal transfer position and shading correction data that does not depend on the horizontal transfer position. As a result, even in the moving image mode in which thinning or cropping is performed, correction can be performed with two shading correction data regardless of the thinning rate and the number of crop positions.

  Even in an imaging apparatus that requires a mode for changing the horizontal transfer frequency or changing the HBLK period, correction is performed after separating the shading correction data depending on the horizontal transfer position and the shading correction data not depending on the horizontal transfer position as described above. To do. This eliminates the need to prepare shading correction data for the number of modes. Specifically, shading correction data that does not depend on the horizontal transfer position is associated with horizontal transfer positions that have different clock cycles or HBLK periods, and shading is corrected together with the shading correction data that depends on the horizontal transfer position. (Third read mode and fourth read mode) Thereby, shading correction data that can be corrected when the clock frequency is changed can be generated.

  In the above embodiment, by performing the HBLK period and the horizontal transfer period at the same time, the shading correction data in the moving image mode is separated into shading correction data that depends on the horizontal transfer position and shading correction data that does not depend on the horizontal transfer position. An example of correction is described.

  However, with respect to the reading method of the image sensor in which the HBLK period and the horizontal transfer period do not overlap, if the power supply voltage of the read circuit fluctuates due to the driving pulse in the HBLK period and has not yet converged in the horizontal transfer period. It is effective to separate and correct.

[Second Embodiment]
An embodiment in which the above-described driving method of the image sensor is applied to a digital camera which is an image pickup apparatus will be described with reference to FIG.

  FIG. 9 is a block diagram illustrating a schematic configuration of an imaging apparatus according to the second embodiment of the present invention.

  In FIG. 9, reference numeral 1001 denotes a lens unit that forms an optical image of a subject on the image sensor 1005, and zoom control, focus control, aperture control, and the like are performed by the lens driving device 1002. Reference numeral 1003 denotes a mechanical shutter which is controlled by the shutter control means 1004.

  Reference numeral 1005 denotes an image sensor for taking in the subject imaged by the lens unit 1001 as an image signal. An image signal processing circuit 1006 amplifies the image signal output from the image sensor 1005, performs A / D conversion for analog-digital conversion, performs various corrections on the image data after A / D conversion, and compresses the data. It is. The above-described correction data is generated by the imaging signal processing circuit 1006 and correction processing is performed.

  A timing generation circuit 1007 is a driving unit that outputs various timing signals to the imaging element 1005 and the imaging signal processing circuit 1006. Reference numeral 1009 denotes a control circuit for controlling various calculations and the entire image pickup apparatus. Reference numeral 1008 denotes a memory for temporarily storing image data. Reference numeral 1010 denotes an interface for performing recording or reading on a recording medium. Reference numeral 1011 denotes a detachable recording medium such as a semiconductor memory for recording or reading image data. Reference numeral 1012 denotes an interface for communicating with an external computer or the like.

  Next, the operation at the time of shooting in the image pickup apparatus shown in FIG. 9 will be described.

  When the main power supply (not shown) of the image pickup apparatus is turned on, the power supply of the control system circuit such as the control circuit 1009 is turned on, and the power supply of the image pickup system circuit such as the image pickup signal processing circuit 1006 is turned on. Next, when a release button (not shown) is pressed, the control circuit 1009 calculates a distance to the subject by extracting a high frequency component based on a signal output from the distance measuring device 1014. Thereafter, the lens driving device 1002 drives the lens unit 1001 to determine whether it is in focus. When it is determined that the lens unit is not in focus, the lens unit is driven again to perform distance measurement. Then, after the in-focus state is confirmed, the photographing operation starts.

  When the photographing operation is completed, the image signal output from the image sensor 1005 is subjected to processing such as amplification and A / D conversion by the image signal processing circuit 1006 and written to the memory by the control circuit 1009. Data stored in the memory 1008 is recorded on a removable recording medium 1011 such as a semiconductor memory through the recording medium control I / F unit 1010 under the control of the control circuit 1009. Further, the image may be processed by directly inputting to a computer or the like through the external I / F unit 1012.

  Next, shading correction executed by the imaging signal processing circuit 1006 will be described with reference to FIG.

  FIG. 10 is a flowchart showing a flow of shading correction executed by the imaging signal processing circuit 1006 of FIG.

  The shading correction circuit of the imaging signal processing circuit 1006 determines whether the image is captured in the full screen mode (step S801). As a result of the determination, if it is determined that the image is not captured in the full screen mode, the process proceeds to step S805. On the other hand, when it is determined that the image is captured in the full screen mode, the correction data 1 includes a predetermined coefficient (gain) according to conditions such as temperature, readout gain, output level, power supply voltage, and current value flowing through the column circuit. ) Is determined (step S802). If it is not necessary to multiply by a coefficient as a result of this determination, the correction data 1 is subtracted from the image data to correct shading depending on the horizontal transfer position (step S803). On the other hand, when it is necessary to multiply by a coefficient, shading correction depending on the horizontal transfer position is performed by subtracting data obtained by multiplying the correction data 1 by the coefficient from the image (step S804).

  In step S805, the correction data 1 is converted into the correction data 3 by the parameter X determined by the number of pixels skipped by the crop and the thinning rate (step S805). Next, it is determined whether or not it is necessary to multiply the correction data 3 by a predetermined coefficient (gain) according to conditions such as temperature, readout gain, output level, power supply voltage, and current value flowing through the column circuit (step). S806). As a result of this determination, if there is no need to multiply by a coefficient, the correction data 3 is subtracted from the image data to correct shading depending on the horizontal transfer position (step S807). On the other hand, when it is necessary to multiply by a coefficient, shading correction dependent on the horizontal transfer position is performed by subtracting data obtained by multiplying the correction data 3 by the coefficient from the image (step S808).

  Next, in step S809, it is determined whether or not the horizontal transfer frequency and the position of the drive pulse during the HBLK period are changed from when the shading correction data 1 and 2 are acquired (step S809). If the result of this determination is that there has been no change, processing proceeds to step S814. On the other hand, when the change is made, the correction data 2 is converted into the correction data 4 according to the parameter T and the position from the clock buffer (step S810).

  Next, it is determined whether or not it is necessary to multiply the correction data 4 by a predetermined coefficient (gain) according to conditions such as temperature, readout gain, output level, power supply voltage, and current value flowing through the column circuit (step S811). . As a result of this determination, if there is no need to multiply by a coefficient, the correction data 4 is subtracted from the image data to perform shading correction independent of the horizontal transfer position (step S812). On the other hand, when it is necessary to multiply by a coefficient, shading correction independent of the horizontal transfer position is performed by subtracting data obtained by multiplying the correction data 4 by the coefficient from the image (step S813).

  In step S814, it is determined whether or not it is necessary to multiply the correction data 2 by a predetermined coefficient (gain) according to conditions such as temperature, readout gain, output level, power supply voltage, and current value flowing through the column circuit. If it is not necessary to multiply by a coefficient as a result of this determination, the correction data 2 is subtracted from the image data to correct shading that does not depend on the horizontal transfer position (step S815). On the other hand, when it is necessary to multiply by a coefficient, shading correction independent of the horizontal transfer position is performed by subtracting data obtained by multiplying the correction data 2 by the coefficient from the image (step S816). Thereafter, when the shading correction depending on the horizontal transfer position and the shading correction independent of the horizontal transfer position are performed, the correction ends.

  As described above, by performing shading correction, it is possible to generate and correct shading correction data corresponding to a plurality of modes from two pieces of shading correction data.

  The object of the present invention can also be achieved by executing the following processing. That is, a storage medium that records a program code of software that realizes the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU, MPU, etc.) of the system or apparatus is stored in the storage medium. This is the process of reading the code. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention.

  Moreover, the following can be used as a storage medium for supplying the program code. For example, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM or the like. Alternatively, the program code may be downloaded via a network.

  Further, the present invention includes a case where the function of the above-described embodiment is realized by executing the program code read by the computer. In addition, an OS (operating system) running on the computer performs part or all of the actual processing based on an instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Is also included.

  Furthermore, the following cases are included in the present invention as a configuration capable of realizing the functions of the above-described embodiments. That is, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing.

101 Pixel unit 102 Row selection circuit 103 Column readout circuit 104 Column memory 105 Column selection circuit 106 Output line 107 Column memory 2
1006 Imaging signal processing circuit 1009 Control circuit

Claims (9)

A pixel that photoelectrically converts light into an electrical signal is arranged in the vertical and horizontal directions, and is an image pickup device that outputs signals from the pixels in the vertical and horizontal directions by a plurality of drive pulses, and outputs them horizontally in the nth row. An image sensor that starts a horizontal blanking period of the (n + 1) th row during the period;
A first shading correction for correcting shading dependent on the horizontal transfer position and a second shading correction for correcting shading independent of the horizontal transfer position for the image signal output from the image sensor. Correction means to perform,
Storage means for storing a first shading correction value for each column of the image sensor for performing the first shading correction and a second shading correction value for performing the second shading correction; An imaging device comprising: A first readout mode for reading out an image signal from the image sensor and a second readout mode in which the number of horizontal transfer pixels is different from the first readout mode;
The correction means uses a third shading correction value and a second shading correction value obtained by converting the first shading correction value according to the number of horizontal transfer pixels in the second readout mode. The imaging apparatus according to claim 1, wherein shading correction is performed.   3. The image pickup apparatus according to claim 2, wherein the second readout mode is a thinning mode for thinning out pixels, an addition mode for adding pixels, or a crop mode for skipping reading of pixels.   The imaging apparatus according to claim 1, wherein the correction unit converts the second shading correction value into a fourth shading correction value according to a pulse position or a horizontal transfer frequency in a vertical transfer period. A third readout mode having a vertical transfer period or a clock cycle different from that of the first readout mode;
The correction means converts the second shading correction value into a fourth shading correction value according to a pulse position or a horizontal transfer frequency in a vertical transfer period, and in the third readout mode, The imaging apparatus according to claim 2, wherein shading correction is performed using a shading correction value and the fourth shading correction value. A first readout mode for reading out an image signal from the imaging device, a second readout mode in which the number of horizontal transfer pixels is different from the first readout mode,
A fourth read mode having a vertical transfer period or a clock period different from that of the second read mode;
The correction means uses a third shading correction value and a second shading correction value obtained by converting the first shading correction value according to the number of horizontal transfer pixels in the second readout mode. To correct shading,
Converting the second shading correction value into a fourth shading correction value according to a pulse position or a horizontal transfer frequency in a vertical transfer period;
The imaging apparatus according to claim 1, wherein shading correction is performed using the third shading correction value and the fourth shading correction value in the fourth readout mode.   Among the data for generating the correction value at the time of driving in the first readout mode, the first shading correction value and the second shading correction value are set in accordance with specific frequency components or specific amplitude data. The imaging apparatus according to claim 2, wherein the imaging apparatus is separated.   The correction unit generates the first shading correction value from the image obtained in the second readout mode, and the first shading from shading data obtained from the image obtained in the first readout mode. The imaging apparatus according to claim 2, wherein data obtained by subtracting a correction value is used as the second shading correction value. A pixel that photoelectrically converts light into an electrical signal is arranged in the vertical and horizontal directions, and is an image pickup device that outputs signals from the pixels in the vertical and horizontal directions by a plurality of drive pulses, and outputs them horizontally in the nth row. A method of controlling an imaging apparatus having an imaging element that starts a horizontal blanking period of the (n + 1) th row during a period,
A first shading correction value for each column of the image sensor for correcting a shading dependent on a horizontal transfer position and a shading independent of a horizontal transfer position are corrected for an image signal output from the image sensor. A control method comprising: a correction step of performing shading correction based on a second shading correction value for the purpose.