JP6318497B2 - Image processing apparatus, imaging apparatus, and program - Google Patents

Description

  The present invention relates to an image processing device, an imaging device, and a program.

  Conventionally, various methods for creating an image to be output to a monitor, a printer, or the like from an image taken with an electronic camera or the like have been considered. For example, when creating an output color space image from the sensor RGB, the color space of the sensor RGB is converted to a narrower color space. In this way, if the sensor RGB is converted as it is into the output color space (in addition to sRGB, for example, AdobeRGB, etc.) using a 3 × 3 color conversion matrix, Negative values and overflow values will occur. Further, when these values are clipped at 0 value or the maximum display value, there is a problem that the luminance is lowered and the gradation is lost or the hue is changed. Therefore, the invention of Patent Document 1 discloses a technique for converting a color outside the reproducible color gamut into the color gamut using a three-dimensional table.

JP 2000-165692 A

  However, the invention of Patent Document 1 has a problem that not only the data amount of the three-dimensional table increases but also the operation scale increases.

  The present invention has been made in view of the above problems, and realizes a suitable color reproducibility with a simple configuration without changing luminance and hue even for colors outside the color gamut in the output color space. With the goal.

An image processing apparatus which is an example of the present invention is an image processing apparatus that creates an output image from a color image output from an imaging device, an acquisition unit that acquires the color image signal, and the color image signal A signal conversion unit that converts a luminance signal and a plurality of color difference signals; and a pixel of interest in which color coordinates exist outside a color gamut reproducible in the color space of the output image, and the luminance signal is maintained, A saturation adjustment unit that adjusts the saturation while maintaining the hue of the target pixel by adjusting the plurality of color difference signals while maintaining the ratio of the plurality of color difference signals, and the saturation adjustment The unit adjusts the color difference signal based on clipping processing of the first color component of the first color component and the second color component of the target pixel to the color gamut, and the second color component Regarding the adjustment of the color component, the first Processing based on whether the clip processing the color component is different.

  The signal conversion unit converts the color image signal into a YCbCr signal, and the saturation adjustment unit maintains a Y signal among the YCbCr signals, and also includes a Cb signal and a Cr signal. The Cb signal and the Cr signal may be adjusted while maintaining the ratio.

  Further, the color image signal is an RGB signal, and the saturation adjustment unit is based on a clipping process of the first color component to the color gamut in the RGB signal of the target pixel. Based on the first adjustment unit that adjusts the color difference signal, and the clipping process to the color gamut of the second color component different from the first color component among the RGB signals of the target pixel, A second adjustment unit that adjusts the color difference signal after adjustment by the first adjustment unit, and a first color component different from the first color component and the second color component among the RGB signals of the target pixel. And a third adjustment unit that adjusts the color difference signal after the adjustment by the second adjustment unit based on the clipping process of the three color components to the color gamut.

  An imaging apparatus that is an example of the present invention includes an imaging unit that captures a color image and the above-described image processing apparatus.

A program that is an example of the present invention is a program that creates an output image from a color image output from an image sensor, the process of obtaining the color image signal, a luminance signal and a plurality of signals of the color image. In the target pixel having color coordinates outside the color gamut that can be reproduced in the color space of the output image, the luminance signal is maintained, and the ratio of the plurality of color difference signals is set. In the state of maintaining, by adjusting the plurality of color difference signals, the process of adjusting the saturation while maintaining the hue of the pixel of interest , respectively, is executed by the computer, the process of adjusting the saturation, Of the first color component and the second color component of the pixel of interest, the color difference signal is adjusted based on the clipping process of the first color component to the color gamut, and the second color component is adjusted. In Information, performs different processing based on whether the first clip processing color components of.

  According to the present invention, it is possible to achieve suitable color reproducibility with a simple configuration without changing luminance and hue even for colors outside the color gamut in the output color space.

The figure which shows the structural example of the electronic camera of 1st Embodiment. 1 is a flowchart showing an operation example of the electronic camera of the first embodiment. Flowchart showing an operation example of the electronic camera of the first embodiment (continued) The figure which shows the gradation conversion curve G1 applied by the 1st gradation conversion process The figure which shows the gradation conversion curve G2 applied by a 2nd gradation conversion process Diagram explaining out-of-gamut clip processing Another diagram explaining out-of-gamut clip processing The figure which shows the structural example of the image processing apparatus in 2nd Embodiment.

<Description of First Embodiment>
FIG. 1 is a diagram illustrating a configuration example of the electronic camera according to the first embodiment which is an example of an image processing apparatus and an imaging apparatus.

  The electronic camera 11 includes a photographing optical system 12, an imaging unit 13, an image processing engine 14, a first memory 15, a second memory 16, a recording I / F 17, a display unit 18, and an operation unit 19. I have. Here, the imaging unit 13, the first memory 15, the second memory 16, the recording I / F 17, the display unit 18, and the operation unit 19 are each connected to the image processing engine 14.

  The imaging unit 13 is a module that captures (captures) an image of a subject formed by the imaging optical system 12. For example, the imaging unit 13 includes an imaging device that performs photoelectric conversion, and a signal processing circuit that performs analog signal processing, A / D conversion processing, and the like on the output of the imaging device. Here, for example, RGB color filters are arranged in the pixels of the image sensor according to a known Bayer array, and image signals corresponding to the respective colors are output by color separation in the color filters. Thereby, the imaging part 13 can acquire a color image at the time of imaging | photography. Note that image data captured by the imaging unit 13 is input to the image processing engine 14.

  The image processing engine 14 is a processor that comprehensively controls the operation of the electronic camera 11, and performs image processing such as color interpolation, gradation conversion, white balance correction, edge enhancement, and noise removal on image data. Apply. The image processing engine 14 functions as a signal conversion unit 21 and a saturation adjustment unit 22 by executing a program (the operations of the signal conversion unit 21 and the saturation adjustment unit 22 will be described later).

  The first memory 15 is a memory that temporarily stores data of each image, and is configured by, for example, an SDRAM that is a volatile storage medium. The second memory 16 is a memory that stores a program executed by the image processing engine 14 and various data used in the program, and is configured by a non-volatile memory such as a flash memory, for example.

  The recording I / F 17 has a connector for connecting the nonvolatile storage medium 20. The recording I / F 17 executes writing / reading of image data with respect to the storage medium 20 connected to the connector. The storage medium 20 is, for example, a hard disk or a memory card incorporating a semiconductor memory. In FIG. 1, a memory card is illustrated as an example of the storage medium 20.

  The display unit 18 is a display device that displays various images. The display unit 18 performs, for example, live view display of an image based on the output of the imaging unit 13 and reproduction display based on an output from the storage medium 20. In addition, the operation unit 19 includes a switch that receives various user operations (for example, an instruction to shoot a subject, an instruction to change setting of brightness adjustment, and the like).

  Next, an operation example of the electronic camera of the first embodiment will be described with reference to the flowcharts of FIGS. 2 and 3. In the first embodiment, an example of adjusting the saturation of a color image will be described. 2 and 3 is started when the image processing engine 14 executes a program when a still image is captured.

  Step # 101: The image processing engine 14 causes the imaging unit 13 to capture a recording still image in response to a user's shooting instruction. As a result, the image processing engine 14 acquires a color image to be processed from the imaging unit 13. Note that the color image at the step # 101 is a RAW image before color interpolation, and the signal value of each pixel corresponds to one of RGB components.

  Step # 102: The image processing engine 14 performs known white balance adjustment and color interpolation (Bayer interpolation) on the acquired color image. Note that all the RGB components are arranged in each pixel of the color image by the color interpolation of # 102.

  Step # 103: The image processing engine 14 designates a pixel of interest for performing saturation adjustment in the color image. Here, the image processing engine 14 sequentially designates all pixels of the color image as the target pixel. In addition, when changing the target pixel, the image processing engine 14 sequentially specifies the target pixel from left to right one line at a time starting from the upper left corner of the image.

  Step # 104: The image processing engine 14 performs a first gradation conversion process using a standard sRGB gamma gradation conversion curve G1 (equivalent to 1 / 2.2) on the pixel value of the target pixel. FIG. 4 shows a gradation conversion curve G1 applied in the first gradation conversion process. The horizontal axis in FIG. 4 is the input pixel value (output of the image sensor) before gradation conversion, and the vertical axis in FIG. 4 is the output pixel value after gradation conversion.

  Step # 105: The signal converter 21 converts the color space of the pixel of interest from RGB to YCbCr. In the process of # 105, the luminance signal Y is generated from the RGB signal values after gradation conversion is performed with G1 while maintaining the color space (sensor RGB) of the image sensor. For this reason, in the above-described processing, there is no occurrence of a gradation step in the high saturation portion, which is caused by matrix conversion from sensor RGB to sRGB.

For example, the signal conversion unit 21 in # 105 may obtain the YCbCr signal value from the RGB signal value of the target pixel by the following equations (1) to (3).
Y = kry * R + kgy * G + kby * B (1)
Cb = -krcb * R-kgcb * G + kbcb * B (2)
Cr = krcr * R-kgcr * G-kbcr * B (3)
In kry, kgy, kby, krcb, kgcb, kbcb, krcr, kgcr, and kbcr in the above formulas (1) to (3), coefficients optimized using color charts are applied.

  By the way, an image composed of YCbCr signals can reproduce a wider range than an output color space (for example, an sRGB color space which is a color space of a display system). For this reason, depending on the contents of the image to be processed (color image acquired in # 101), some of the pixels may have their color coordinates outside the color gamut in the output color space. In step # 108, which will be described later, out-of-gamut clip processing is performed to correct pixels whose color coordinates are out of the color gamut into the color gamut.

  Step # 106: The image processing engine 14 performs a second gradation conversion process on the luminance signal Y using the gradation conversion curve G2. Note that a gradation conversion curve G2 applied in the second gradation conversion process is shown in FIG. The horizontal axis in FIG. 5 is an input pixel value before gradation conversion, and the vertical axis in FIG. 5 is an output pixel value after gradation conversion. This gradation conversion curve G2 is an S-shaped curve that reduces the gradation change in the low luminance portion and the high luminance portion. In the second gradation conversion process, contrast enhancement of the image and black tightening that compresses the gradation of the low luminance part are performed.

  Step # 107: The image processing engine 14 performs known edge enhancement processing and noise reduction processing on the image after the second gradation conversion processing, respectively.

Step # 108: The saturation adjusting unit 22 performs out-of-gamut clipping processing based on the luminance signal Y and the color difference signals (Cb, Cr) of the target pixel. The out-of-gamut clipping process will be described with reference to the flowchart of FIG. The out-of-gamut clipping process will be described by taking the sRGB color space as an example of the output color space. The relationship between the YCbCr color space and the sRGB color space is expressed by the following equations (4) to (6).
Y = Kr * R + (1-Kr-Kb) * G + Kb * B (4)
Cb = 1/2 * (BY) / (1-Kb)… (5)
Cr = 1/2 * (RY) / (1-Kr) (6)
Coefficients optimized using color charts are applied to Kr and Kb in the above formulas (4) to (6).

Furthermore, the following formulas (7) to (9) are obtained by converting the above formulas (4) to (6).
B = 2 * Cb * (1-Kb) + Y (7)
R = 2 * Cr * (1-Kr) + Y (8)
G = (Y-Kr * R-Kb * B) / (1-Kr-Kb) (9)
The saturation adjustment unit performs out-of-gamut clip processing using the above-described Expressions (4) to (9). Hereinafter, image data in which each color component is represented by 8 bits (0 to 255) will be described as an example of a color image.

Step # 201: The saturation adjusting unit 22 calculates a ratio between the value of the color difference signal Cb (hereinafter referred to as Cb value) and the value of the color difference signal Cr (hereinafter referred to as Cr value). The ratio cbc between the Cb value and the Cr value is obtained by the following equation (10).
cbc = Cr / Cb (10)
Step # 202: The saturation adjusting unit 22 obtains the R value using the value of the luminance signal Y (hereinafter referred to as Y value) and Cr value of the pixel of interest and the above-described equation (8). When the coefficient Kr optimized using the above-described color chart is 0.299, the R value based on Expression (8) is as shown in Expression (11) below.
R = Y + 1.402 * Cr (11)
Step # 203: The saturation adjusting unit 22 determines whether or not the R value calculated in # 202 is a negative value (is a value less than 0). If the R value is a negative value, the saturation adjusting unit 22 determines that clipping of the R value is necessary, and the process proceeds to # 204. On the other hand, when the R value is not a negative value, the saturation adjusting unit 22 shifts the processing to # 206 described later.

Step # 204: The saturation adjusting unit 22 sets the R value to 0, and calculates the Cr value after clipping the R value using the Y value of the target pixel and the above-described equation (6). For the luminance signal Y, the original Y value is maintained. Further, when R = 0 and the coefficient Kr = 0.299 as exemplified in # 202, the Cr value based on the equation (6) is as the following equation (12).
Cr = -Y / 1.402… (12)
Step # 205: The saturation adjusting unit 22 calculates the Cb value by the following equation (13) based on the ratio cbc calculated in # 201 and the Cr value after clipping the R value calculated in # 204. To do. Thus, by calculating the Cb value after clipping the R value, the ratio between the Cb value and the Cr value is maintained.
Cb = Cr / cbc (13)
Step # 206: The saturation adjusting unit 22 determines whether or not the R value calculated in # 202 exceeds 255. When the R value exceeds 255, the saturation adjusting unit 22 determines that clipping is necessary because the R value is saturated, and the process proceeds to # 207. On the other hand, when the R value is 255 or less, the saturation adjusting unit 22 determines that the clip is unnecessary because the R value is 0 or more and 255 or less, and shifts the processing to # 209 described later.

Step # 207: The saturation adjusting unit 22 sets the R value to 255, and calculates the Cr value after clipping the R value using the Y value of the target pixel and the above-described equation (6). For the luminance signal Y, the original Y value is maintained. Further, when R = 255 and the coefficient Kr = 0.299 as exemplified in # 202, the Cr value based on the equation (6) is expressed by the following equation (14).
Cr = (255-Y) /1.402… (14)
Step # 208: The saturation adjusting unit 22 uses the ratio cbc calculated in # 201 and the Cr value after clipping the R value calculated in # 207 to calculate Cb according to the equation (13) described in # 205. Calculate the value. Thus, by calculating the Cb value after clipping the R value, the ratio between the Cb value and the Cr value is maintained.

Step # 209: The saturation adjusting unit 22 obtains the B value using the Y value and Cb value of the target pixel and the above-described equation (7). Note that the original value is always used for the Y value. As for the Cb value, the value calculated in # 205 or # 208 is used when the R value is clipped, and the original value is used when the R value is not clipped. Further, when the coefficient Kb optimized using the above-described color chart is 0.114, the B value based on the equation (7) is expressed by the following equation (15).
B = Y + 1.772 * Cb… (15)
Step # 210: The saturation adjusting unit 22 determines whether or not the B value calculated in # 209 is a negative value (is a value less than 0). If the B value is a negative value, the saturation adjusting unit 22 determines that clipping of the B value is necessary, and the process proceeds to # 211. On the other hand, when the B value is not a negative value, the saturation adjusting unit 22 shifts the processing to # 213 described later.

Step # 211: The saturation adjusting unit 22 sets the B value to 0, and calculates the Cb value after clipping the B value using the Y value of the target pixel and the above-described equation (5). For the luminance signal Y, the original Y value is maintained. Further, when B = 0 and Kb = 0.114 as exemplified in # 209, the Cb value based on the equation (5) is expressed by the following equation (16).
Cb = -Y / 1.772… (16)
Step # 212: The saturation adjusting unit 22 calculates the Cr value by the following equation (17) based on the ratio cbc calculated in # 201 and the Cb value after clipping the B value calculated in # 211. To do. Thus, by calculating the Cr value after clipping the B value, the ratio between the Cb value and the Cr value is maintained.
Cr = cbc * Cb (17)
Step # 213: The saturation adjusting unit 22 determines whether or not the B value calculated in # 209 exceeds 255. When the B value exceeds 255, the saturation adjusting unit 22 determines that clipping is necessary because the B value is saturated, and the process proceeds to # 214. On the other hand, when the B value is 255 or less, the saturation adjusting unit 22 determines that the clip is unnecessary because the B value is 0 or more and 255 or less, and shifts the processing to # 216 described later.

Step # 214: The saturation adjusting unit 22 sets the B value to 255, and calculates the Cb value after clipping the B value using the Y value of the pixel of interest and the above-described equation (5). For the luminance signal Y, the original Y value is maintained. Further, when B = 255 and Kb = 0.114 as exemplified in # 209, the Cb value based on the equation (5) is represented by the following equation (18).
Cb = (255-Y) /1.772… (18)
Step # 215: Based on the ratio cbc calculated in # 201 and the Cb value after clipping the B value calculated in # 214, the saturation adjusting unit 22 uses the equation (17) described in # 212 to obtain Cr. Calculate the value. Thus, by calculating the Cr value after clipping the B value, the ratio between the Cb value and the Cr value is maintained.

Step # 216: The saturation adjusting unit 22 obtains the G value by using the Y value, Cb value, and Cr value of the target pixel and the above-described equations (7) to (9). Note that the original value is always used for the Y value. As for the Cb value, when the B value is clipped, the value calculated at # 211 or # 214 is used, and when the B value is not clipped and the R value is clipped, # 205 or The value calculated in # 208 is used, and when neither the B value nor the R value is clipped, the original value is used. As for the Cr value, when the B value is clipped, the value calculated at # 212 or # 215 is used, and when the B value is not clipped and the R value is clipped, # 204 or The value calculated in # 207 is used, and when neither the B value nor the R value is clipped, the original value is used. Further, when the coefficient Kr = 0.299 and the coefficient Kb = 0.114 optimized using the above-described color chart, the G value based on the equations (7) to (9) is expressed by the following equation (19). .
G = Y-0.3441 * Cb-0.7141 * Cr (19)
Step # 217: The saturation adjusting unit 22 determines whether or not the G value calculated in # 216 is a negative value (a value less than 0). If the G value is a negative value, the saturation adjusting unit 22 determines that clipping of the G value is necessary, and the process proceeds to # 218. On the other hand, when the G value is not a negative value, the saturation adjusting unit 22 shifts the processing to # 220 described later.

Step # 218: The saturation adjusting unit 22 sets the G value to 0, the ratio cbc calculated in # 201, the Y value of the target pixel, and the R value clipped in # 204 or # 207 (the R value is clipped). If not, the B value clipped at # 211 or # 214 (or the original B value if the B value is not clipped), the G value clipped to 0, Using the equations (4) to (6), the Cb value after clipping the G value is calculated. For the luminance signal Y, the original Y value is maintained. Further, when G = 0 and the coefficient Kr = 0.299 and the coefficient Kb = 0.114 as exemplified in # 216, the Cb value based on the expressions (4) to (6) is expressed by the following expression (20). become.
Cb = -Y / (-0.3441-0.7141 * cbc)… (20)
Step # 219: Based on the ratio cbc calculated in # 201 and the Cb value after clipping the G value calculated in # 218, the saturation adjusting unit 22 uses the equation (17) described in # 212 to obtain Cr. Calculate the value. Thus, by calculating the Cr value after clipping the G value, the ratio between the Cb value and the Cr value is maintained.

  Step # 220: The saturation adjusting unit 22 determines whether or not the G value calculated in # 216 exceeds 255. When the G value exceeds 255, the saturation adjusting unit 22 determines that clipping is necessary because the G value is saturated, and the process proceeds to # 221. On the other hand, when the G value is 255 or less, the saturation adjusting unit 22 determines that the clip is unnecessary because the G value is 0 or more and 255 or less, and ends the series of processes.

Step # 221: The saturation adjusting unit 22 sets the G value to 255, the ratio cbc calculated in # 201, the Y value of the target pixel, and the R value clipped in # 204 or # 207 (the R value is clipped). If not, the B value clipped at # 211 or # 214 (or the original B value if the B value is not clipped), the G value clipped to 255, and the above Using the equations (4) to (6), the Cb value after clipping the G value is calculated. For the luminance signal Y, the original Y value is maintained. Further, when G = 255 and the coefficient Kr = 0.299 and the coefficient Kb = 0.114 as exemplified in # 216, the Cb value based on the expressions (4) to (6) is expressed by the following expression (21). become.
Cb = (255-Y) / (-033441-0.7141 * cbc)… (21)
Step # 222: The saturation adjusting unit 22 uses the ratio cbc calculated in # 201 and the Cb value after clipping the G value calculated in # 221 to calculate Cr according to the equation (17) described in # 212. A value is calculated, and a series of processing ends. Thus, by calculating the Cr value after clipping the G value, the ratio between the Cb value and the Cr value is maintained.

  The out-of-gamut clipping process described above will be described with reference to the schematic diagrams of FIGS. 6 and 7 show the YCbCr space. The horizontal axis in FIG. 6 indicates the Cb value and the Cr value, and the vertical axis indicates the Y value. On the other hand, the horizontal axis in FIG. 7 indicates the Cb value, and the vertical axis indicates the Cr value. A region A1 surrounded by a square in FIG. 6 indicates a color gamut that can be reproduced in the sRGB color space.

  For example, since the pixel P (1) shown in FIG. 6 has the color coordinates in the above-described color gamut, none of the values change in the out-of-gamut clipping process. Further, for example, the pixel P (2) and the pixel P (3) shown in FIG. 6 are out of the color gamut, so that the pixel P (2-a) and the pixel P ( 3-a). As a result, as shown in FIG. 6, the saturation is reduced while the Y value indicating the luminance is maintained. Further, when the pixel P (2) is adjusted to the pixel P (2-a) by the out-of-gamut clipping process, as shown in FIG. 7, the ratio between the Cb value and the Cr value is maintained. As a result, the saturation is adjusted while maintaining the hue. The same applies to the pixel P (3).

  Note that in the out-of-gamut clip processing described with reference to FIGS. 3, 6, and 7, an example is shown in which processing is performed in the order of B value, R value, and G value, but the present invention is limited to this example. Not.

  Step # 109: The image processing engine 14 determines whether or not the processing of all the pixels of the color image has been completed. If the above requirement is satisfied (YES side), the process proceeds to # 110. On the other hand, if the above requirement is not satisfied (NO side), the process returns to # 103 and the image processing engine 14 repeats the above operation.

  Step # 110: The image processing engine 14 performs ring tone enhancement processing, noise removal processing, JPEG compression processing, etc. on the color image as necessary, and then stores the color image data in the storage medium 20 via the recording I / F 17. Record.

  The electronic camera according to the first embodiment acquires a color image signal output from an image sensor, converts the acquired color image signal into a luminance signal and a plurality of color difference signals, and reproduces it in the color space of the output image. In the target pixel whose color coordinates exist outside the possible color gamut, the luminance signal is maintained and the hue of the target pixel is adjusted by adjusting the plurality of color difference signals while maintaining the ratio of the plurality of color difference signals. Adjust saturation while maintaining. As a result, in the first embodiment, it is possible to achieve suitable color reproducibility with a simple configuration without changing the luminance and hue even for colors outside the color gamut in the output color space. In particular, by maintaining the luminance, the gradation is improved as compared with the case of performing a simple clipping process as in the prior art.

<Description of Second Embodiment>
FIG. 8 is a diagram illustrating a configuration example of the image processing apparatus according to the second embodiment. The image processing apparatus according to the second embodiment is a computer in which a program for performing saturation adjustment processing on an input image is installed.

  A computer 31 illustrated in FIG. 8 includes a data reading unit 32, a storage device 33, a CPU 34, a memory 35, an input / output I / F 36, and a bus 37. The data reading unit 32, the storage device 33, the CPU 34, the memory 35, and the input / output I / F 36 are connected to each other via a bus 37. Furthermore, an input device 38 (keyboard, pointing device, etc.) and a monitor 39 are connected to the computer 31 via an input / output I / F 36. The input / output I / F 36 accepts various inputs from the input device 38 and outputs display data to the monitor 39.

  The data reading unit 32 is used when reading data of a color image to be processed (RAW image before color interpolation) or a program from the outside. The data reading unit 32 communicates with, for example, a reading device (such as an optical disk, a magnetic disk, or a magneto-optical disk reading device) that acquires data from a removable storage medium, or an external device based on a known communication standard. A communication device to perform (USB interface, LAN module, wireless LAN module, etc.).

  The storage device 33 is a storage medium such as a hard disk or a non-volatile semiconductor memory. The storage device 33 stores the above program and various data necessary for executing the program. The storage device 33 can also store image data read from the data reading unit 32.

  The CPU 34 is a processor that comprehensively controls each unit of the computer 31. The CPU 34 functions as the image processing engine 14, the signal conversion unit 21, and the saturation adjustment unit 22 of the first embodiment or the second embodiment by executing the program.

  The memory 35 temporarily stores various calculation results in the program. The memory 35 is, for example, a volatile SDRAM.

  Here, in the image processing apparatus according to the second embodiment, the CPU 34 acquires a color image to be processed from the data reading unit 32 or the storage device 33. Then, the CPU 34 executes the processes of # 102 to # 109 and # 201 to # 211 of the first embodiment. In the second embodiment, substantially the same effect as that of the first embodiment can be obtained.

<Supplementary items of the embodiment>
(Supplement 1): In the above embodiment, an example in which subject extraction is performed using YCbCr data of an image has been described. However, the present invention is not limited to the YCbCr color space, and can be applied to other color spaces (L * a * b * and the like).

(Supplement 2): In the above embodiment, the example in which each function of the image processing apparatus is realized by software by a program has been described. However, in the image processing apparatus of the present invention, each function of the signal conversion unit 21 and the saturation adjustment unit 22 is set to, for example, an ASIC (Application Specific Integrated Circuit).
It may be realized in hardware using

  From the above detailed description, features and advantages of the embodiments will become apparent. It is intended that the scope of the claims extend to the features and advantages of the embodiments as described above without departing from the spirit and scope of the right. Further, any person having ordinary knowledge in the technical field should be able to easily come up with any improvements and modifications, and there is no intention to limit the scope of the embodiments having the invention to those described above. It is also possible to use appropriate improvements and equivalents within the scope disclosed in.

DESCRIPTION OF SYMBOLS 11 ... Electronic camera, 12 ... Imaging | photography optical system, 13 ... Imaging part, 14 ... Image processing engine, 15 ... 1st memory, 16 ... 2nd memory, 17 ... Recording I / F, 18 ... Display part, 19 ... Operation part 20 ... storage medium, 21 ... signal conversion unit, 22 ... saturation adjustment unit, 31 ... computer, 32 ... data reading unit, 33 ... storage device, 34 ... CPU, 35 ... memory, 36 ... input / output I / F, 37 ... Bus, 38 ... Input device, 39 ... Monitor

Claims (5)

An image processing apparatus for creating an output image from a color image output from an image sensor,
An acquisition unit for acquiring a signal of the color image;
A signal converter for converting the color image signal into a luminance signal and a plurality of color difference signals;
In the target pixel in which color coordinates exist outside the color gamut reproducible in the color space of the output image, while maintaining the luminance signal and maintaining the ratio of the plurality of color difference signals, the plurality of color differences by adjusting the signal, and a saturation adjusting unit for adjusting the color saturation while maintaining the hue of the pixel of interest,
The saturation adjustment unit adjusts the color difference signal based on clipping processing of the first color component to the color gamut of the first color component and the second color component of the target pixel, An image processing apparatus that performs different processing for adjusting the second color component based on whether or not the first color component has been clipped . The image processing apparatus according to claim 1.
The signal conversion unit converts the color image signal into a YCbCr signal,
The saturation adjustment unit among signals of the YCbCr, while maintaining signal Y, while maintaining the ratio of the Cb signal and Cr signal, you adjust the signal of the signal and the Cr of the Cb images processing device. The image processing apparatus according to claim 1 or 2,
The color image signal is an RGB signal,
The saturation adjustment unit
A first adjustment unit that adjusts the color difference signal based on clipping processing of the first color component to the color gamut among the RGB signals of the target pixel;
The color difference signal after the adjustment by the first adjustment unit based on the clipping process to the color gamut of the second color component different from the first color component among the RGB signals of the target pixel A second adjustment unit for adjusting
Based on the clipping process to the color gamut of the third color component different from the first color component and the second color component among the RGB signals of the target pixel, the second adjustment unit images processing device that having a third adjustment section for adjusting the color difference signals after the adjustment. An imaging unit for imaging a color image;
The image processing apparatus and includes that an imaging apparatus according to any one of claims 3 to claim 1. A program for creating an output image from a color image output from an image sensor,
Processing for obtaining a signal of the color image;
Processing for converting the color image signal into a luminance signal and a plurality of color difference signals;
In the target pixel in which color coordinates exist outside the color gamut reproducible in the color space of the output image, while maintaining the luminance signal and maintaining the ratio of the plurality of color difference signals, the plurality of color differences by adjusting the signals, respectively cause the computer to execute a process of adjusting the color saturation, the while maintaining the hue of the pixel of interest,
In the process of adjusting the saturation, the color difference signal is adjusted based on a clipping process to the color gamut of the first color component of the first color component and the second color component of the target pixel. The second color component is adjusted according to whether or not the first color component has been clipped .

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