JP5202375B2 - Imaging apparatus, image processing method, and program - Google Patents

Description

  The present invention relates to an imaging apparatus, an image processing apparatus, an image processing method, a program, and a computer-readable storage medium that determine a specific scene.

  2. Description of the Related Art In recent years, imaging apparatuses having a scene discrimination function that can automatically discriminate a shooting scene without manually setting camera shooting settings have become widespread. With the scene discrimination function, it is possible to discriminate which of the specific scenes, such as “Night Scene”, “Backlight”, “Evening Scene”, etc. Function. For example, a method is known in which scene determination is performed in consideration of a tendency of arrangement of luminance information and color information corresponding to a specific scene in an image, and also taking into account variations in their position and area ratio (patent) Reference 1).

JP-A-2005-310123

  In the conventional scene discrimination as described above, discrimination is performed based on luminance information and color information. However, depending on the scene, a high-intensity subject such as the sun may be taken within the angle of view, and smearing may occur. As a result, the area of high luminance and achromatic color may increase due to the effect of smear, and the conditions of luminance information and color information as a specific scene cannot be satisfied, and as a result, the scene cannot be identified.

  The present invention has been made in view of such problems, and it is an object of the present invention to provide an imaging apparatus and the like that can perform high-precision scene determination by determining a specific scene in consideration of occurrence of smear. And

The imaging apparatus according to the present invention includes an imaging unit that acquires an image, a luminance information acquisition unit that acquires luminance information of the image, a color information acquisition unit that acquires color information of the image, and a smear that occurs in the image. The ratio of blocks satisfying a predetermined condition is within a predetermined range by looking at the smear region detecting means for detecting a smear region, and the luminance information and the color information for each block with respect to the image divided into a plurality of blocks. Scene discrimination means for discriminating that the scene is a specific scene in some cases, wherein the scene discrimination means sets the predetermined range smaller as the detected smear area is larger.
The image processing apparatus of the present invention includes an image acquisition unit that acquires an image, a luminance information acquisition unit that acquires luminance information of the image, a color information acquisition unit that acquires color information of the image, and the image. Smear area detection means for detecting a smear area where smear has occurred, and the luminance information and the color information for each block with respect to the image divided into a plurality of blocks, the ratio of blocks satisfying a predetermined condition is predetermined. A scene discriminating unit that discriminates that the scene is a specific scene when it is within the range, wherein the scene discriminating unit sets the predetermined range to be smaller as the detected smear region is larger. Features.
The image processing method of the present invention includes an image acquisition step of acquiring an image, a luminance information acquisition step of acquiring luminance information of the image, a color information acquisition step of acquiring color information of the image, and the image. A smear area detecting step for detecting a smear area where smear has occurred, and the luminance information and the color information for each block with respect to the image divided into a plurality of blocks, and the ratio of blocks satisfying a predetermined condition is predetermined. A scene discrimination step for discriminating that the scene is a specific scene when it is within the range of the range, and in the scene discrimination step, the larger the smear area detected by the smear area detection step, the greater the predetermined range. It is characterized by being set small.
The program of the present invention includes an image acquisition step of acquiring an image, a luminance information acquisition step of acquiring luminance information of the image, a color information acquisition step of acquiring color information of the image, and a smear in the image. A smear region detecting step for detecting a smear region that has occurred, and the luminance information and the color information for each block with respect to the image divided into a plurality of blocks, and the ratio of blocks satisfying a predetermined condition is within a predetermined range A program for causing a computer to execute a scene determination step for determining that the scene is a specific scene, and the larger the smear region detected by the smear region detection step in the scene determination step, The predetermined range is set to be small.
The computer-readable storage medium of the present invention is a computer-readable storage medium storing the program described above.

  According to the present invention, it is possible to determine a scene with high accuracy even in an image having smear.

It is a block diagram which shows the function structural example of the digital camera which concerns on embodiment of this invention. It is a flowchart which shows the flow of the process which detects the smear area | region which concerns on embodiment of this invention. It is the figure which showed typically the flow of the process which detects the smear area | region which concerns on embodiment of this invention. It is a flowchart which shows the flow of the process which performs the scene discrimination | determination based on embodiment of this invention. It is the figure which showed the relationship of each block in an image used in the case of the process which performs the scene discrimination | determination concerning embodiment of this invention. It is a figure for demonstrating typically the calculation of the gravity center position of a sky area | region used in the case of the process which performs the scene discrimination | determination concerning embodiment of this invention. It is the figure which showed an example of the histogram of a saturation used in the case of the process which performs the scene discrimination | determination concerning embodiment of this invention. It is the figure which showed an example of the histogram of the hue used in the case of the process which performs the scene discrimination | determination concerning embodiment of this invention.

<Configuration of imaging device>
In the present embodiment, a case where a digital camera (hereinafter referred to as the present digital camera) is used as an example of the imaging apparatus according to the embodiment will be described. FIG. 1 is a block diagram illustrating a functional configuration example of the digital camera.

  The operation unit 101 includes switches and buttons that are operated by an operator of the digital camera to input various instructions to the digital camera. One of the operations included in the operation unit 101 is a shutter switch. When the shutter switch is half-pressed, a signal SW1 is notified from the operation unit 101 to the control unit 102. When the shutter switch is fully pressed, the signal SW2 is notified from the operation unit 101 to the control unit 102.

  The control unit 102 controls the operation of each unit shown in the figure, and controls each unit in response to an instruction from the operation unit 101 or the like. When the control unit 102 receives the notification of the signal SW1 and the signal SW2 from the operation unit 101 as described above, each unit is controlled to execute processing according to these notifications.

  The vertical / horizontal position detecting unit 103 detects whether the orientation of the digital camera is a vertical shooting position or a horizontal shooting position.

  The CCD unit 104 receives light incident through the lens 105 and the exposure mechanism 106, and accumulates and outputs charges corresponding to the amount of light. A CMOS sensor may be used instead of the CCD. The A / D conversion unit 107 performs sampling, gain adjustment, A / D conversion, and the like on the analog image signal output from the CCD unit 104 and outputs it as a digital image signal. The image processing unit 108 performs various types of image processing on the digital image signal output from the A / D conversion unit 107 and outputs a processed digital image signal. For example, the image processing unit 108 converts the digital image signal received from the A / D conversion unit 107 into a YUV image signal and outputs the YUV image signal.

  The scene determination unit 109 acquires a digital image signal from the image processing unit 108 (image acquisition). Based on the digital image signal, the scene to be photographed is a plurality of specific scenes such as “backlight” and “evening scene”. Determine which scene it is. The scene discrimination unit 109 discriminates a scene based on, for example, a YUV image signal received from the image processing unit 108.

  If the scene determination unit 109 determines a specific scene, the image processing unit 108 performs image processing that is optimal for photographing the determined scene. For example, if it is determined to be “backlight”, the exposure of a subject located near the center of the screen is controlled so that the brightness approaches an appropriate value in preference to the surrounding area, or “sunset” is determined. If so, the color signal of the image is adjusted so that the reddish color of the photographed image becomes vivid. If it is determined to be “sport”, exposure control is performed so that the exposure time is shorter than in other scenes so that the subject image does not blur, and focus adjustment is performed by tracking the subject that has been determined as the main subject. To do.

  The smear detection unit 110 detects the presence / absence of smear and the area where the smear has occurred based on the digital image signal received from the image processing unit 108, and outputs the detection result to the scene determination unit 109. In response to this, the scene discriminating unit 109 switches the mode of the scene discrimination processing, and details thereof will be described later.

  The EF processing unit 111 instructs the flash unit 112 to flash on. When the control unit 102 determines that the flash is necessary, the EF processing unit 111 receives the instruction, controls the flash unit 112, and causes the flash unit 112 to emit light.

  The EVF display unit 113 is configured by a small liquid crystal screen or the like, and displays an image according to the image data processed by the image processing unit 108. The format conversion unit 114 converts the format of the digital image signal (image data) output from the image processing unit 108 into a format such as JPEG, and outputs it to the image recording unit 115. The image recording unit 115 performs processing for recording the image data subjected to format conversion received from the format conversion unit 114 in a memory (not shown) in the digital camera, an external memory inserted in the digital camera, or the like.

  The external connection unit 116 functions as an interface for connecting the digital camera to an external device such as a PC (personal computer) or a printer.

  The AF processing unit 117 operates the lens 105 to focus on the subject, and the AE processing unit 118 controls the exposure mechanism 106 so that the screen has an optimal exposure.

  The digital camera is configured as described above. Here, the operation of the digital camera when imaging is performed using the digital camera will be described.

  First, when an operator of the digital camera turns on a power switch included in the operation unit 101, the control unit 102 detects this and supplies power to each unit constituting the digital camera. When power is supplied to each unit constituting the digital camera, a shutter (not shown) is opened, and light enters the CCD unit 104 via the lens 105 and the exposure mechanism 106. The CCD unit 104 reads the electric charge accumulated by the incident light and outputs it to the A / D conversion unit 107 as an analog image signal.

  The A / D conversion unit 107 performs sampling, gain adjustment, A / D conversion, and the like on the analog image signal output from the CCD unit 104 and outputs it as a digital image signal. The digital image signal is output to the image processing unit 108. The image processing unit 108 performs various image processing on the digital image signal output from the A / D conversion unit 107, and outputs a processed digital image signal. .

  Based on the digital image signal output from the image processing unit 108, the scene determination unit 109 determines which scene among a plurality of specific scenes such as “backlight” and “evening scene” is to be captured. As described above, when the scene determination unit 109 determines a specific scene, the image processing unit 108 performs image processing that is optimal for photographing the scene. The scene determination unit 109 acquires luminance information and color information (including saturation information and hue information) from the digital image signal output from the image processing unit 108, and uses this to determine the scene. . Here, the process of acquiring the luminance information and the color information corresponds to the process of the luminance information acquisition unit and the color information acquisition unit in the present invention.

  Further, since the image processing unit 108 outputs the processed image data to the EVF display unit 113, the EVF display unit 113 displays an image according to the processed image data. Also, based on the image data acquired by the image processing unit 108, the AF processing unit 117 operates the lens 105 to focus on the subject, and the AE processing unit 118 provides an optimal exposure of the screen. Thus, the exposure mechanism 106 is controlled.

  When the processing so far is completed, the control unit 102 repeats the above processing as long as the signal SW1 is not notified from the shutter switch included in the operation unit 101 (that is, notification of half-pressing of the shutter switch). On the other hand, when the control unit 102 receives a notification of the signal SW1 from the shutter switch, AF and AE processes are performed using the image data at this time, and the optimum focus and exposure setting conditions are acquired.

  Then, the control unit 102 returns the processing to the signal SW1 and repeats the above processing unless receiving the notification of the signal SW2 from the shutter switch (that is, the notification of full pressing of the shutter switch).

  On the other hand, when the control unit 102 receives the notification of the signal SW2 from the shutter switch, the control unit 102 shifts to a photographing process and first determines whether or not to emit the flash. Whether or not to emit the flash may be determined in advance by using the operation unit 101 and may be determined by reading the setting data, or may be automatically determined by detecting the darkness of the surroundings. You may do it.

  As a result of determining whether or not to emit the flash, when the flash is emitted, the control unit 102 controls the EF processing unit 111 to cause the flash unit 112 to perform pre-emission, calculate the emission amount, and calculate the EF frame. Processing such as weighting is performed. Then, the flash unit 112 is caused to emit light with the light emission amount calculated by the pre-light emission, and image shooting is performed. In the case of non-flash emission, the process proceeds to the following process without the above dimming control.

  In the actual photographing, light from the outside world enters the CCD unit 104 via the lens 105 and the exposure mechanism 106. Therefore, the photoelectric conversion element constituting the CCD unit 104 has a charge corresponding to the amount of the incident light. Accumulates. The CCD unit 104 reads the accumulated electric charge and outputs it as an analog image signal to the A / D conversion unit 107.

  The A / D conversion unit 107 performs sampling, gain adjustment, A / D conversion, and the like on the analog image signal output from the CCD unit 104 and outputs it as a digital image signal. The image processing unit 108 performs various types of image processing on the digital image signal output from the A / D conversion unit 107, and outputs a processed digital image signal. The format conversion unit 114 outputs the digital image signal, converts the format of the digital image signal (image data) output from the image processing unit 108 into a format such as JPEG, and outputs the converted format to the image recording unit 115. The image recording unit 115 performs a process of recording the format-converted image data in a predetermined memory.

  Through the processing described above, the digital camera according to the present embodiment performs shooting processing. Here, the digital camera can perform scene determination with high accuracy by performing scene determination in consideration of a smear area during the photographing process. Hereinafter, details of the process for performing scene determination will be described in consideration of the smear region. Note that smear is a state where charges are saturated when a certain area of the CCD unit 104 is irradiated with light, which affects other areas, and a white-colored portion appears in a band shape in the image. Such a phenomenon.

<Detection of smear area>
A method for detecting a smear area in an image performed by the digital camera will be described. FIG. 2 is a flowchart showing a process for detecting a smear region according to this embodiment, and FIG. 3 is a diagram schematically showing the flow of the flowchart. In addition, the smear detection part 110 performs the process which concerns on the following detection. The smear detection unit 110 is controlled by the control unit 102 and executes processing. The control unit 102 includes a CPU and the like. The processing of the smear detection unit 110 is realized by reading a program from a ROM (not shown) and executing processing using a RAM (not shown) as a work area.

The flowchart of FIG. 2 is as follows.
(Step S201)
First, the smear detection unit 110 divides the image into a plurality of blocks. The number of divisions may be a total of 135 divisions, for example, 15 divisions in the horizontal direction and 9 divisions in the vertical direction. FIG. 3 is a diagram showing images (301 to 306) schematically showing images. In the example shown here, the image is divided into 15 parts in the horizontal direction and 9 parts in the vertical direction.

(Step S202)
Next, the smear detection unit 110 scans in the horizontal direction from the upper left block of the paper in the image (see arrows in FIGS. 3 and 301).

(Step S203)
Next, the smear detection unit 110 calculates the average value of the luminance in the block, and if the value is equal to or greater than the threshold value (TH_SmearY), the process proceeds to step S204, and if less than TH_SmearY, the process proceeds to step S208.

(Step S204)
If the average value of the luminance of the block is equal to or higher than TH_SmearY (step S203), the smear detection unit 110 scans in the vertical direction from the block (see arrows in FIG. 3, 302).

(Step S205)
Next, as in step S203, the smear detection unit 110 calculates the average value of the luminance in the block, and if the value is equal to or greater than TH_SmearY, the process proceeds to step S206, and if less than TH_SmearY, proceeds to step S208.

(Step S206)
If the average luminance value of the block is equal to or higher than TH_SmearY (step S205), the smear detection unit 110 scans in the vertical direction. If the lowest block in the image has been scanned, the process proceeds to step S207. If the lowest block has not been scanned, the process returns to step S204.

(Step S207)
If the average values of the luminance values of the respective blocks in one column are all equal to or higher than TH_SmearY in step S206, the smear detection unit 110 regards the column as a smear region (FIG. 3, 303). Then, the area determined as the smear area is recorded, and the process proceeds to step S208.

(Step S208)
Then, the smear detection unit 110 determines whether or not scanning has been performed in the horizontal direction from the upper left block in the image to the upper right block in the paper. When it is determined that the average value of the luminance in the block is less than TH_SmearY and the scanning to the rightmost block of the image is completed, the process proceeds to step S209. Alternatively, when it is determined that there is a smear area and scanning is completed up to the upper right block on the page, the process proceeds to step S209. If the rightmost block on the page has not been scanned yet, the process returns to step S202, and the top row is scanned again in the horizontal direction (see the arrow in FIG. 3, 304).

(Step S209)
When all the blocks in the top row of the paper in the image are scanned, the smear detection unit 110 calculates the width of each smear region (see double-ended arrows in FIG. 3 and 305). When the calculation is completed, the process proceeds to step S210.

(Step S210)
Next, the smear detection unit 110 regards the peripheral area as a false color area because there is a possibility that a false color is generated around the smear occurrence position. The false color area may be set to the left and right of each smear area, for example, and the left and right widths may be the same width as the smear area (FIG. 3, 306, double-ended arrow A: smear area, double-ended arrows B, C: false color) region).

  Through the above processing, it is possible to detect a smeared region. As a smear detection method, the output level of the shielded vertical optical black portion outside the effective pixel region of the CCD unit 104 may be regarded as a smear-only output signal, and the smear region may be detected. The processing described here corresponds to a processing example of a smear region detecting means in the present invention.

<Scene discrimination>
Next, processing for determining a specific scene from an image related to the digital camera will be described. Here, as an example, a method for determining a sunset scene will be described. FIG. 4 is a flowchart showing processing for determining an evening scene according to the present embodiment. It should be noted that the scene determination unit 109 executes the processes related to the following determination. The scene determination unit 109 is controlled by the control unit 102 and executes processing. The processing of the scene determination unit 109 is realized by the processing of the control unit 102, similarly to the smear detection unit 110 described above.

(Step S401)
First, the scene determination unit 109 calculates the subject luminance value (Bv value) of each pixel in the image and the average luminance value of the entire image. Further, the image is divided into a plurality of regions, and the subject distance (distance information) in each region is calculated. Then, it is determined whether or not all of these satisfy the conditions for proceeding to evening scene discrimination. Here, it is assumed that a predetermined threshold is set in advance as to whether or not the condition is satisfied. If not satisfied, evening scene discrimination is stopped and the process proceeds to discrimination of another scene (not shown).

(Step S402)
Next, the scene determination unit 109 divides the image into a plurality of blocks. The number of divisions may be, for example, a total of 135 divisions, 15 divisions in the horizontal direction and 9 divisions in the vertical direction, similar to the detection of the smear region described above.

(Step S403)
Next, the scene determination unit 109 calculates an average value of luminance, saturation, and hue (luminance information, color information) for each block obtained in step S402. In the present embodiment, information on luminance, saturation, and hue of each block is divided into “sunset color block”, “sky blue block”, “intermediate color block”, and “other color blocks”. For example, a sunset color block is a hue belonging to red to yellow and has a saturation in a certain range, a sky blue block is a hue belonging to blue and having a saturation in a certain range, and an intermediate color block is a hue belonging to red to yellow but having a saturation. Suppose that the degree does not satisfy the sunset color block. The other color blocks may not be applied to any of the sunset color block, sky blue block, and intermediate color block. Further, a threshold value for satisfying each block may be determined according to the luminance value.

(Step S404)
Next, the scene determination unit 109 determines a smear area and a false color area. Whether or not the smear region is detected is determined by the method shown in FIG.

(Step S405)
Next, when the presence / absence of smear and the area where the smear has occurred are determined, the scene determination unit 109 determines whether or not to use the information for sunset scene determination for each block divided in the image. For example, blocks that are not used in evening scene discrimination may be low luminance blocks, high luminance blocks, white blocks, smear area blocks, false color blocks, and face area blocks. The low luminance, high luminance, and white blocks are determined based on the luminance value, saturation, and hue of each block. Further, if a face detection function for detecting a face portion that is a part of the subject is provided, and the face is detected by this function, the area may not be used. Blocks that are not used in the sunset scene determination are basically determined in step S403 that none of the conditions of “sunset color block”, “sky blue block”, and “intermediate color block” is satisfied. It is classified as “Block”. As a result, it is possible to discriminate a scene without using information that may affect evening scene discrimination such as a smear region, and a specific scene can be discriminated with high accuracy. Hereinafter, a block used for evening scene discrimination will be referred to as a “searchable block”.

  Here, FIG. 5 is a diagram showing the relationship of each block in the image used when performing evening scene discrimination in the present embodiment.

  As shown in FIG. 5, first, all blocks in the image are divided into a total of four types: sunset color blocks, intermediate color blocks, sky blue blocks, and other color blocks. The sky blue block is divided into a high saturation sky blue block and a low saturation sky blue block according to the saturation. Then, a low luminance block, a high luminance block, a white block, a smear area block, a false color block, and a face area block are extracted from the other color blocks, and set as “unsearchable blocks”.

  In addition, blocks other than non-searchable blocks are referred to as “searchable blocks”. Further, among the other blocks, those that are not determined as “unsearchable blocks” are divided into high saturation blocks and low saturation blocks according to the saturation. Note that the threshold value for determining whether the sky blue block has high saturation or low saturation may be different from the threshold value for determining whether the other blocks have high saturation or low saturation. The above sunset color block, intermediate color block, sky blue block, and low saturation block are defined as “effective blocks” (covered with dotted lines). In the present embodiment, these blocks are appropriately selected to execute evening scene discrimination.

(Step S406)
Next, the scene determination unit 109 uses the luminance information, saturation information, and hue information of each block in the image after step S406. Here, it is regarded that the sunset scene determination condition is not satisfied if a certain percentage or more of all the blocks have uniform information. Uniform information indicates that the luminance information, saturation information, and hue information of each block are similar to each other. For example, when shooting a red wall on one side, even if each block satisfies the sunset color block condition, it will be difficult to distinguish it as an evening scene if there are many blocks with uniform information. This is because it can happen.

(Step S407)
Next, in step S407, the scene determination unit 109 calculates how much white area is present. This area is the white block selected in step S405. If a certain percentage or more of all the blocks satisfy the condition of the white block, it is regarded that the sunset scene determination condition is not satisfied. Here, the value indicated by the ratio serving as the determination criterion changes according to the width occupied by the smear region and the false color region determined in step S404. In the area excluding the smear area and the false color area, luminance information, saturation information, and hue information corresponding to the subject occupying the area are obtained. On the other hand, the smear region and the false color region include not only the region where the high-luminance subject causing the smear exists but also the upper and lower regions thereof. In other words, even if the subject that occupies the upper and lower areas where the high-brightness subject that causes smear exists satisfies the conditions of the sunset block and sky blue block if there is no smear, there is a high-brightness subject in that row Therefore, it becomes a smear area or a false color area. As described above, since smear is generated, the ratio of blocks to be determined (here, white blocks) may be smaller than when smear does not occur. Therefore, as the width of the smear region increases, The ratio value of the above-described determination criterion is reduced. Of course, instead of the ratio of blocks to be determined, the absolute number of blocks to be determined may be used as a criterion, and the absolute number of the criterion may be reduced as the width of the smear region increases. . In this way, in this embodiment, a specific scene can be discriminated with higher accuracy.

(Step S408)
Next, in step S408, the scene determination unit 109 calculates how much low saturation is present. This region is a block that does not satisfy the non-searchable block and has low saturation among the other color blocks selected in step S405. If a certain percentage or more of the searchable blocks satisfy the condition of the low saturation block, it is regarded that the sunset scene determination condition is not satisfied.

(Step S409)
Next, in step S409, the scene determination unit 109 calculates how many intermediate color regions are present. This area is the intermediate color block selected in step S405. If a certain proportion or more of the effective blocks satisfy the condition of the intermediate color block, it is regarded that the sunset scene determination condition is not satisfied.

(Step S410)
Next, in step S410, the scene determination unit 109 calculates how many sky blue regions have high saturation. This region is a block having high saturation among the sky blue blocks selected in step S405. If a certain proportion or more of the effective blocks satisfy the condition of a sky blue block with high saturation, it is considered that the sunset scene determination condition is not satisfied.

(Step S411)
Next, in step S411, the scene determination unit 109 calculates how many high-saturation areas satisfying certain conditions. This area is a block that does not satisfy the valid block among the searchable blocks selected in step S405. If a certain percentage or more of the blocks having a certain saturation in the searchable block satisfy the conditions of the other color blocks, it is regarded that the sunset scene determination condition is not satisfied.

(Step S412)
Next, the scene determination unit 109 calculates the gravity center position of the sky region in step S412. In the present embodiment, the position of the center of gravity is calculated based on the number and arrangement of blocks that are considered to be sky blue. FIG. 6 is a diagram for schematically explaining the calculation of the gravity center position of the sky region. Here, first, as shown in FIG. 6, blocks satisfying the sky blue condition are calculated (blocks having different colors in the figure). Then, the number of blocks satisfying the sky blue condition is obtained for each row. The evaluation value of the barycentric position is obtained by multiplying the number of blocks in each row by the row number and adding up all the rows. For example, if the row numbers are counted from the bottom in the image, the higher the evaluation value, the higher the center of gravity position of the sky region is in the image. When the vertical / horizontal position detection unit 103 determines that the position is the vertical shooting position, the center-of-gravity position may be calculated by adding blocks satisfying the sky blue condition for each column instead of each row. Here, if the calculated position of the center of gravity is within a certain ratio from the upper part of the image, the condition for determining the evening scene is satisfied, and if it is close to the lower part of the image, the condition for determining the evening scene is not satisfied. FIG. 6 shows an example of an evaluation value calculation method.

(Step S413)
Next, in step S413, the scene determination unit 109 determines a saturation histogram from the saturation information for the block that satisfies the sunset color block calculated in step S403. FIG. 7 is a diagram showing an example (701 to 705) of a saturation histogram. In the example illustrated in FIG. 7, the horizontal axis of the histogram is saturation, and may be, for example, 0 to 100 in increments of 5. The vertical axis of the histogram represents the ratio of the number of blocks of each saturation to the number of blocks satisfying the sunset color block with respect to the effective block.
Here, when a part of the histogram is interrupted as indicated by 702, or when the width of the histogram is limited within a certain range as indicated by 703, it is assumed that the sunset scene determination is not satisfied. Further, when the maximum value of the histogram is equal to or greater than a certain value as indicated by 704, the region of the portion that is not simply decreased is scanned from the maximum value portion of the histogram to the left and right as indicated by 705, and is not less than a certain value. , It is assumed that the evening scene discrimination is not satisfied. That is, if any one of these four determinations is true, the sunset scene determination is not satisfied, and for example, a scene determined to have a predetermined shape such as 701 satisfies the sunset scene determination.

(Step S414)
Next, in step S414, the scene determination unit 109 determines a hue histogram from the hue information for a block that satisfies a specific condition. Here, the specific condition may be, for example, a condition that satisfies one or more of four kinds of conditions of hues belonging to red to yellow, low luminance, high luminance, and white. FIG. 8 is a diagram showing an example of a hue histogram (801 to 803). In the example shown in FIG. 8, the horizontal axis of the histogram is the hue, and may be, for example, 100 to 200 in increments of 5. The vertical axis of the histogram is the ratio of the number of blocks of each hue to the number of blocks that satisfy a specific condition. Further, the specific condition may be, for example, a block that satisfies any one of a searchable block, a low luminance block, a high luminance block, and a white block.
Here, when the maximum value of the histogram is equal to or greater than a certain value as indicated by 802, the region of the portion that is not simply decreased is scanned from the maximum value portion of the histogram to the left and right as indicated by 803. In the case where there is the above, it is assumed that the evening scene discrimination is not satisfied. That is, if any one of these two determinations is true, the sunset scene determination is not satisfied, and for example, a scene determined to have a predetermined shape such as 801 satisfies the sunset scene determination.

(Step S415)
Next, in step S415, the scene discrimination unit 109 scans each block in the image in the horizontal direction, and discriminates brightness and color having a large proportion of each line. In this embodiment, each line is classified into a total of eight types: a low luminance line, a high luminance line, a low saturation line, a sky blue line, a sunset color line, an intermediate color line, other color lines, and a non-target line. As a classification method, first, each block in each line is divided into a plurality of types based on luminance information and color information.
The types to which each block belongs include the low luminance block, high luminance block, sky blue block, sunset color block, intermediate color block specified in step S405, low saturation block specified in step S408, and other color blocks other than these. There is. When the blocks are divided into the above seven types, the ratio of each classification in one line and the classification with the highest ratio are calculated, and each line is classified according to the brightness and color based on the result. As a method of classifying each line, for example, when a low-luminance block has a certain ratio or more in one line and the ratio is larger than any other classification, the line is set as a low-luminance line. Similarly, similar conditions are set for a high luminance line, a low saturation line, a sky blue line, a sunset color line, an intermediate color line, and other color lines. The certain ratio in the condition may be set to a different threshold depending on each classification. Also for this fixed ratio, the value decreases as the width of the smear region determined in step S404 increases. Those that do not belong to any line are classified as excluded lines. If it is determined from the position information from the vertical / horizontal position detection unit 103 that the digital camera is in the vertical shooting position, it is changed to the vertical direction instead of the horizontal direction, and each block in the image is scanned to scan each line. Try to classify.

(Steps S416 to S419)
Next, in steps S416 to S419, the scene determination unit 109 determines the extent of the high luminance line (S416), sky blue line (S417), low saturation line (S418), and other color lines (S419) in the image. Calculate if there is. If a certain percentage or more of the horizontal lines in the image satisfy the respective conditions, it is regarded that the sunset scene determination condition is not satisfied. About this fixed ratio, you may set a different value to each, such as a high-intensity line and a sky blue line.

(Step S420)
Next, in step S420, the average saturation and average hue of the sunset color block are calculated. The average saturation and average hue of the block satisfying the sunset color block are calculated, and if the values do not fall within a certain range, it is regarded that the sunset scene determination condition is not satisfied.

(Step S421)
Next, in step S421, the scene determination unit 109 calculates how many sunset color blocks are present. If blocks that satisfy the sunset color condition are below a certain percentage of the effective blocks, it is considered that the sunset scene determination condition is not satisfied.

(Step S422)
In step S401 and step S406 to step S421, it is calculated whether or not the sunset scene determination condition is satisfied. In step S422, the scene determination unit 109 determines the sunset scene determination result based on whether all the previous sunset scene determination conditions are satisfied. If all the determination conditions are satisfied, the process proceeds to step S423. If even one of the determination conditions is not satisfied, the process proceeds to step S424.

(Step S423, Step S424)
The scene discrimination unit 109 discriminates that scene as an evening scene when all the evening scene discrimination conditions are satisfied. On the other hand, if even one of the scenes does not satisfy the sunset scene determination condition, it is determined that the scene is not a sunset scene.

  Although the method for discriminating the sunset scene has been described above, the threshold used for each discrimination condition may be determined according to the situation at the time of shooting. In addition to the evening scene, a blue sky, a night scene, a backlight, or the like may be determined by designating a determination condition. Furthermore, depending on the type of scene to be determined, the information is not limited to luminance information and color information in the image. In addition to scenes such as blue sky, macro mode, which is a close-up mode according to the subject distance, and person mode is set when a person's face is detected in the image, and scenes "blue sky + macro", " It can also be determined as a combination of a plurality of scenes such as “night view + person”.

  The conditions for determining the blue sky include, for example, the Bv value in the image, the distance between the subject and the imaging device, the distribution in the image of the block ratio belonging to blue calculated from the luminance, saturation, and hue information, and the color temperature. It is also possible to discriminate using the calculated result. As the night scene discrimination conditions, for example, the Bv value in the image, the distance between the subject and the imaging device, the average luminance, and the distribution in the image of the block ratio belonging to black calculated from the luminance, saturation, and hue information are used. It is possible to discriminate even. Further, if the imaging apparatus has a function of detecting the movement of the imaging apparatus and the movement of the subject, the movement information may be added to the scene determination condition. Of course, in the blue sky determination and the night scene determination, a high-luminance subject may be shot within the angle of view, so the determination method may be switched depending on the presence or absence of smear.

<Image processing during scene discrimination>
Next, an image processing method for scene determination according to the digital camera will be described.

  In the present embodiment, one or more of exposure correction, color correction, gamma correction, and dark area correction in the image is set according to the determined scene. If it is determined that the shooting scene is a sunset scene, the exposure is slightly under-exposed, the saturation is slightly increased, and gamma correction and dark part correction are performed. It is possible to enhance the sunset scene by further enhancing the saturation of the region belonging to red to yellow and slightly underexposure. Furthermore, in a scene with a low contrast ratio, it is possible to improve contrast by finely adjusting the gradation by gamma correction. In addition, for dark areas in an image generated by slightly underexposure, it is possible to expect an improvement effect by dark part correction. By performing image processing with exposure and color control in this way, it is possible to perform image processing suitable for a sunset scene when shooting with an imaging device.

  As described above, the image processing method when the scene is determined to be an evening scene has been described. However, the image processing according to the scene may be performed by specifying a condition for determining other than the evening scene. For example, when a blue sky scene is determined, image processing suitable for the scene, such as increasing the saturation of blue, can be performed. Further, when a night scene is determined, image processing may be performed such that black is tightened by lowering the gradation of the dark part. Furthermore, if the information on the movement of the imaging device and the movement of the subject is one of the night scene discriminations, it is suitable for night scenes by setting a slow shutter to keep the ISO sensitivity low in night scenes without movement. It is also possible to perform image processing with reduced image quality. In the present embodiment, it is described that exposure correction, color correction, gamma correction, and dark part correction are performed according to the determined scene, but the image processing method is not limited to these.

  As described above, in the digital camera according to the present embodiment, a specific scene is determined in consideration of the occurrence of a smear region. More specifically, when the ratio of the area satisfying the predetermined luminance information and color information is within the predetermined range, it is determined that the sunset determination condition is satisfied, and is determined according to the size of the generated smear area. Thus, the size of the predetermined range is changed. By doing so, the digital camera according to the present embodiment can perform scene discrimination with high accuracy.

  In addition, the specific structure about this invention is not restricted to embodiment mentioned above, The design etc. of the range which does not deviate from the summary of this invention are included.

  In the processing of this embodiment, a storage medium storing software program codes embodying each function may be provided to the system or apparatus. The functions of the above-described embodiments can be realized by the computer (or CPU or MPU) of the system or apparatus reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. As a storage medium for supplying such a program code, for example, a floppy (registered trademark) disk, a hard disk, an optical disk, a magneto-optical disk, or the like can be used. Alternatively, a CD-ROM, CD-R, magnetic tape, nonvolatile memory card, ROM, or the like can be used.

  The functions of the above-described embodiments are not only realized by executing the program code read by the computer. In some cases, an OS (operating system) running on the computer performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. include.

  Further, the program code read from the computer-readable storage medium may be written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. After that, the CPU of the function expansion board or function expansion unit performs part or all of the actual processing based on the instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Is also included.

101 Operation unit 102 Control unit 103 Vertical / horizontal position detection unit 104 CCD unit 105 Lens 106 Exposure mechanism 107 A / D conversion unit 108 Image processing unit 109 Scene determination unit 110 Smear detection unit 111 EF processing unit 112 Flash unit 113 EVF display unit 114 Format Conversion unit 115 Image recording unit 116 External connection unit 117 AF processing unit 118 AE processing unit

Claims (11)

Imaging means for acquiring an image;
Luminance information acquisition means for acquiring luminance information of the image;
Color information acquisition means for acquiring color information of the image;
Smear region detecting means for detecting a smear region where smear is generated in the image;
A scene determination that determines a specific scene when the ratio of blocks that satisfy a predetermined condition is within a predetermined range by looking at the luminance information and the color information for each block with respect to the image divided into a plurality of blocks Means,
The imaging apparatus, wherein the scene determination unit sets the predetermined range to be smaller as the detected smear region is larger. The color information includes saturation information,
The scene discriminating means, when the ratio of blocks satisfying the predetermined condition is within the predetermined range and the histogram for the saturation for each block for the image satisfies the predetermined condition, The imaging apparatus according to claim 1, wherein the imaging apparatus is determined to be a scene. The color information includes hue information,
The scene discriminating unit is configured to detect the specific scene when a ratio of blocks satisfying the predetermined condition is within the predetermined range and a histogram of hue for each block with respect to the image satisfies a predetermined condition. The image pickup apparatus according to claim 1, wherein the image pickup apparatus is discriminated as being.   The scene discriminating unit scans the blocks of the image horizontally so that the ratio of the blocks satisfying the predetermined condition is within the predetermined range, and obtains brightness and color having a large ratio in each line. 2. The specific scene is determined when the number of lines that satisfy a predetermined condition with respect to brightness and color is within a predetermined range derived from the luminance information and the color information. The imaging apparatus of any one of -3. It has a vertical and horizontal position detector that detects whether it is a vertical or horizontal shooting position.
The imaging apparatus according to claim 4, wherein the scene determination unit changes the horizontal scanning direction based on position information output from the vertical / horizontal position detection unit.   The imaging apparatus according to claim 1, wherein the imaging apparatus switches an image processing method at the time of shooting according to the specific scene determined by the scene determination unit.   7. The smear region detecting means divides the image into a plurality of blocks, detects luminance information, color information, and block arrangement for each block, and detects a smear region. The imaging apparatus of Claim 1. Image acquisition means for acquiring images;
Luminance information acquisition means for acquiring luminance information of the image;
Color information acquisition means for acquiring color information of the image;
Smear region detecting means for detecting a smear region where smear is generated in the image;
A scene determination that determines a specific scene when the ratio of blocks that satisfy a predetermined condition is within a predetermined range by looking at the luminance information and the color information for each block with respect to the image divided into a plurality of blocks Means,
The image processing apparatus, wherein the scene determination unit sets the predetermined range to be smaller as the detected smear region is larger. An image acquisition step of acquiring an image;
A luminance information acquisition step of acquiring luminance information of the image;
A color information acquisition step of acquiring color information of the image;
A smear region detecting step for detecting a smear region in which smear is generated in the image;
A scene determination that determines a specific scene when the ratio of blocks that satisfy a predetermined condition is within a predetermined range by looking at the luminance information and the color information for each block with respect to the image divided into a plurality of blocks And having steps,
In the scene determination step, the predetermined range is set to be smaller as the smear region detected in the smear region detection step is larger. An image acquisition step of acquiring an image;
A luminance information acquisition step of acquiring luminance information of the image;
A color information acquisition step of acquiring color information of the image;
A smear region detecting step for detecting a smear region in which smear is generated in the image;
A scene determination that determines a specific scene when the ratio of blocks that satisfy a predetermined condition is within a predetermined range by looking at the luminance information and the color information for each block with respect to the image divided into a plurality of blocks A program for causing a computer to execute steps,
In the scene discrimination step, the predetermined range is set to be smaller as the smear region detected in the smear region detection step is larger.   A computer-readable storage medium storing the program according to claim 10.

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