JP2018147417A - Image processor, image processing method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor capable of satisfactorily correcting imbalance of color while suppressing saturation when any saturation region is generated in a subject.SOLUTION: A shininess correction amount determination section (203) detects a saturated area where color signals are saturated in a predetermined subject area of an input image. The shininess correction amount determination section (203) calculates a color balance normal color signal value in the saturated area when there is no upper limit at which a color signal value saturates and generates a correction value with which the color balance at the corrected color signal value for the saturated area gets color balance at a proper color signal value. A shininess correction processing part (204) corrects an image signal in the saturated area based the generated correction value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an image processing apparatus, an image processing method, and a program for processing captured images.

2. Description of the Related Art Conventionally, in an image pickup device that picks up a subject image and outputs an image pickup signal, an output signal from the pixel is saturated when strong light of a certain level or more is incident on the pixel constituting the element. As described above, a region where a saturated pixel is generated is recognized as a whiteout region. For example, when a person is imaged, light that is strongly reflected on the surface of the skin may cause a phenomenon called “shine” in a part of the area, and the quality of the captured image may be lowered.
Further, in an image sensor that outputs only specific color signals of R (red), G (green), and B (blue), as in a so-called Bayer array, all color signals are not saturated and specific color signals are output. Only the saturation may cause the balance of each color to be lost. When the balance of each color is lost in this way, a coloring phenomenon occurs in that portion, and the original color of the subject may not be obtained.

On the other hand, in Patent Document 1, a specific subject region such as a person is detected from an image, a region close to the color component mainly occupied by the subject (skin color region) is detected from the subject region, and the luminance value of the skin color region is calculated. With reference to this, there is disclosed a technique for correcting so that the luminance is lowered when the luminance value is high.
Japanese Patent Application Laid-Open No. 2004-228561 controls processing for reducing a coloring phenomenon in a saturated portion and color restoration processing in a saturated portion based on an exposure condition actually used at the time of photographing and an appropriate exposure condition at the time of photographing. Thus, a technique for improving the quality of the high luminance part is disclosed.

JP-A-2005-327209 JP 2012-244633 A

However, the technique described in Patent Document 1 does not consider the coloring phenomenon, and in a region where only a specific color signal is saturated, the coloring phenomenon may occur even when correction is performed so as to lower the luminance.
In addition, the technique described in Patent Document 2 depends on the exposure conditions, and correction based on the state of the high-luminance region of the subject cannot be performed.

  SUMMARY An advantage of some aspects of the invention is that it is possible to satisfactorily correct color balance while suppressing saturation that occurs in a subject area.

  The present invention provides a detecting means for detecting a saturated area in which a color signal value is saturated in a predetermined subject area of an input image, and an original color signal in the saturated area when there is no upper limit for saturation of the color signal value. A calculation unit that calculates a color balance of the value; a generation unit that generates a correction amount in which the color balance of the color signal value after correction for the saturation region is a color balance of the original color signal value; and the generated Correction means for correcting the image signal in the saturation region based on the correction amount.

  According to the present invention, it is possible to satisfactorily correct the color balance while suppressing saturation occurring in the subject area.

It is a figure which shows schematic structure of the digital camera of embodiment. It is a figure which shows the detailed structure of an image process part. It is a figure which shows the detailed structure of a shine correction amount determination part. It is a flowchart of the process in a shine correction amount determination part. It is a figure which shows the gain characteristic based on the brightness | luminance used in a shine correction amount determination part.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
The image processing apparatus of the present invention is applied to various cameras such as digital still cameras, digital video cameras, smartphones and tablet terminals having digital camera functions, various information terminals such as personal computers, industrial cameras, in-vehicle cameras, and medical cameras. Applicable. In the present embodiment, an example in which the image processing apparatus of the present invention is applied to a digital camera will be described. The digital camera according to the present embodiment has a function of correcting an image including a high luminance region that is generated when light emitted from a light source is reflected by the surface of a subject.

<First Embodiment>
FIG. 1 is a block diagram illustrating a schematic configuration example of the digital camera according to the first embodiment.
The digital camera of this embodiment includes an optical system 101, an image sensor 102, an A / D conversion unit 103, an image processing unit 104, a face detection unit 105, a recording unit 106, a control unit 107, a memory 108, an operation unit 109, and a display unit. 110 is provided.

  The optical system 101 includes a focus lens, a diaphragm, and a shutter. The optical system 101 drives a focus lens to focus on a subject at the time of photographing, and adjusts an exposure amount by controlling an aperture and a shutter. The image sensor 102 is a photoelectric conversion element such as a CCD or a CMOS that converts the amount of light of the subject image formed on the imaging surface by the optical system 101 into an electric signal by photoelectric conversion. Further, on the imaging surface of the imaging element 102, color filters corresponding to the respective color components of the three primary colors R (red), G (green), and B (blue) are provided for each pixel in a so-called Bayer arrangement. A single color is determined by the plurality of color components of R, G, and B. For this reason, the image sensor 102 outputs an analog image signal composed of color signals of R, G, and B pixels corresponding to the Bayer array. The A / D conversion unit 103 digitizes the input analog image signal and outputs it to the image processing unit 104.

  The image processing unit 104 receives a digitized image signal as an input image. The input image signal is subjected to synchronization processing, white balance correction processing, shine correction processing, gamma processing, and the like. Output. The face detection unit 105 is supplied with an image signal from the image processing unit 104, and for example, a face of a person in the captured image is used as a predetermined subject region used for determination of a target region for the shine correction processing performed by the image processing unit 104 Detect areas.

  The recording unit 106 converts the image signal output from the image processing unit 104 into data in an image format such as JPEG and records it. Alternatively, the recording unit 106 does not perform conversion into an image format, but uses so-called RAW information that is a combination of an image signal captured by the image sensor 102 and digitized by the A / D conversion unit 103 and information at the time of shooting. Etc. are recorded in the data format.

  The control unit 107 performs overall operation control of the digital camera of this embodiment. For example, the control unit 107 calculates a predetermined evaluation value based on the captured image and determines parameters for image processing performed by the image processing unit 104. The memory 108 stores information used by the image processing unit 104 and outputs the information to the image processing unit 104 as necessary under the control of the control unit 107.

  The operation unit 109 is a part where the user gives an operation instruction to the digital camera, and the operation instruction input from the operation unit 109 is input to the control unit 107. The display unit 110 is, for example, a liquid crystal display or the like installed on the back of the housing of the digital camera according to the present embodiment, and is stored in a screen for assisting operations during shooting, a preview image during shooting, and the recording unit 106 The displayed image or the like is displayed.

  FIG. 2 is a block diagram illustrating a detailed configuration of the image processing unit 104. The image processing unit 104 includes a synchronization processing unit 201, a white balance correction processing unit 202, a shine correction amount determination unit 203, a shine correction processing unit 204, and a gamma processing unit 205. In FIG. 2, an A / D conversion unit 103 and a recording unit 106 are also drawn. Hereinafter, the detailed configuration of the image processing unit 104 and the flow of processing will be described with reference to FIG.

  An image signal corresponding to a Bayer array (hereinafter referred to as an input RGB signal) digitally converted by the A / D conversion unit 103 is input to the image processing unit 104 as an input image. The input RGB signal input to the image processing unit 104 is sent to the synchronization processing unit 201. The synchronization processing unit 201 performs synchronization processing on the input RGB signals in the Bayer array, and generates signals composed of R, G, and B colors (hereinafter referred to as color signals R, G, and B) per pixel. This determines the color of one pixel. The color signals R, G, and B generated by the synchronization processing unit 201 are sent to the white balance correction processing unit 202. Based on the white balance gain value calculated by the control unit 107, the white balance correction processing unit 202 adjusts the white balance by applying gains to the color signal values of the color signals R, G, and B, respectively. The color signals R, G, and B that have undergone white balance adjustment are sent to the shine correction amount determination unit 203 and the shine correction processing unit 204.

  Based on the input color signals R, G, B, the shine correction amount determination unit 203 determines the shine correction amounts Rh_out, Gh_out, Bh_out for the respective color signal values. Details of the shine correction amount determination processing by the shine correction amount determination unit 203 will be described later. The shine correction amounts Rh_out, Gh_out, and Bh_out determined by the shine correction amount determination unit 203 are sent to the shine correction processing unit 204.

  The shine correction processing unit 204 corrects the color signals R, G, and B input from the white balance correction processing unit 202 based on the shine correction amounts Rh_out, Gh_out, and Bh_out input from the shine correction amount determination unit 203. I do. The shine correction processing by the shine correction processing unit 204 is performed in the face area of the subject detected by the face detection unit 105 (not shown in FIG. 2). Hereinafter, the color signals after the correction by the correction processing unit 204 are denoted as corrected color signals R ′, G ′, and B ′. Specifically, the shine correction process is a process of subtracting the corresponding shine correction amounts Rh_out, Gh_out, and Bh_out from the input color signal values of the color signals R, G, and B as shown in Expression (1). .

R ′ = R−Rh_out
G ′ = G−Gh_out
B ′ = B−Bh_out (1)

  Then, the shine correction processing unit 204 outputs the corrected color signals R ′, G ′, and B ′ to the gamma processing unit 205. The gamma processing unit 205 performs gamma processing on the input corrected color signals R ′, G ′, and B ′, and outputs the color signals Rg, Gg, and Bg after the gamma processing to the recording unit 106.

FIG. 3 is a block diagram showing a detailed configuration of the shine correction amount determination unit 203.
The shine correction amount determination unit 203 includes a luminance signal generation unit 301, a saturated pixel determination unit 302, a correction target color acquisition unit 303, a shine correction amount calculation unit 304, a saturation signal evaluation unit 305, and a shine correction amount adjustment unit 306. . FIG. 4 is a flowchart showing the flow of processing performed by the shine correction amount determination unit 203. The detailed configuration and processing flow of the shine correction amount determination unit 203 will be described below with reference to FIGS. 3 and 4. In the flowchart of FIG. 4, the processing steps of steps S401 to S408 are abbreviated as S401 to S408, respectively. Further, the process of each step shown in the flowchart of FIG. 4 may be executed by a hardware configuration, or may be realized by a CPU or the like executing a program.

  First, in step S <b> 401, color signals R, G, and B are input from the white balance correction processing unit 202 to the shine correction amount determination unit 203. The color signals R, G, and B are sent to the luminance signal generation unit 301, the saturated pixel determination unit 302, the correction target color acquisition unit 303, the saturation signal evaluation unit 305, and the shine correction amount adjustment unit 306. After S401, the processing of the shine correction amount determination unit 203 proceeds to the processing after S402, but each processing of S402, the next S403, and further S405 may be performed in parallel.

In S402, the correction target color acquisition unit 303 calculates the average value R_ave of each color in the face area detected by the face detection unit 105 (not shown in FIG. 3) from the input color signals R, G, and B. G_ave and B_ave are calculated. Then, the correction target color acquisition unit 303 uses the average values R_ave, G_ave, and B_ave as correction target color signals Rs, Gs, and Bs for the subject (face area) to the shine correction amount calculation unit 304 and the saturation signal evaluation unit 305. Output.
In S403, the luminance signal generation unit 301 calculates the luminance signal Y from the input color signals R, G, and B, and uses the calculated luminance signal Y as the shine correction amount calculation unit 304 and the shine correction amount adjustment unit. Output to 306.

  Next, in S404, the shine correction amount calculation unit 304 firstly uses the correction target color signals Rs, Gs, and Bs acquired by the correction target color acquisition unit 303 in S402, and the complementary color signals R_inv, R of the subject (face area). G_inv and B_inv are calculated. Here, the complementary color is a color having a reverse characteristic of the target color. If the color signal values of the color signals R, G, and B are each in the range of 0 to 255, the complementary color signals R_inv, G_inv, and B_inv can be obtained by Expression (2).

R_inv = 255−Rs
G_inv = 255-Gs
B_inv = 255−Bs (2)

  In S404, the shine correction amount calculation unit 304 refers to the luminance signal Y calculated by the luminance signal generation unit 301 in S403, and calculates the luminance gain signal Ky in which the gain amount increases as the luminance level increases. Further, the shine correction amount calculation unit 304 multiplies the luminance gain signal Ky by the complementary color signals R_inv, G_inv, and B_inv of the color of the subject (face area) as shown in Expression (3), thereby obtaining a reference shine. Correction amounts Rh, Gh, Bh are calculated.

Rh = Ky × R_inv
Gh = Ky × G_inv
Bh = Ky × B_inv (3)

  In S405, the saturated pixel determination unit 302 determines whether or not the signal values of the input color signals R, G, and B are saturated at the target pixel. At this time, the saturated pixel determination unit 302 acquires predetermined threshold values Rth, Gth, and Bth of each color signal stored in advance in the memory 108 (not shown in FIG. 3). Further, the saturated pixel determination unit 302 determines a pixel in which at least one color signal value of the input color signals R, G, and B is equal to or greater than a threshold corresponding to the color signal as a saturated pixel. Then, the saturated pixel determination unit 302 outputs a determination result of whether the target pixel is a saturated pixel and determination signals Is_R_sat, Is_G_sat, Is_B_sat indicating which color signal is saturated at a threshold value or higher. Output to 305.

  Next, in S406, the saturation signal evaluation unit 305 determines how much each color signal value of the saturated pixel is for each color of the saturated pixel determined by the saturation pixel determination unit 302 in S405 if there is no upper limit of the signal value. The original signal value indicating whether the signal level is obtained is calculated. In this case, the saturation signal evaluation unit 305 calculates the original signal value of the saturation pixel using the correction target color signals Rs, Gs, and Bs acquired by the correction target color acquisition unit 303 in S402. That is, the signal value calculated at this time is a value estimated to be the original signal value of the saturated subject (face area).

  Specifically, the saturation signal evaluation unit 305 first sorts the correction target color signals Rs, Gs, and Bs acquired by the correction target color acquisition unit 303 in descending order of the signal level (signal value), and Cs_high, Cs_middle. , Cs_low. Then, the saturation signal evaluation unit 305 calculates the color signal ratios Cs_R1 and Cs_R2 according to a predetermined formula (4). That is, in Expression (4), signal ratios Cs_R1 and Cs_R2 between Cs_low having the smallest signal value among Cs_high, Cs_middle, and Cs_low and other signal values other than Cs_high, Cs_middle, and Cs_low are calculated.

Cs_R1 = Cs_high / Cs_low
Cs_R2 = Cs_middle / Cs_low (4)

  Next, the saturation signal evaluation unit 305 calculates the original signal value of the saturation pixel based on the color signal ratios Cs_R1 and Cs_R2. Here, among the input color signals R, G, and B, color signals corresponding to the respective colors of Cs_high, Cs_middle, and Cs_low are represented as C_high, C_middle, and C_low. It should be noted that at least Cs_low (the signal value with the lowest value) is saturated among Cs_high, Cs_middle, and Cs_low in which the correction target color signals Rs, Gs, and Bs acquired by the correction target color acquisition unit 303 are arranged in descending order of the signal level. No signal value is considered. The saturation signal evaluation unit 305 uses the C_low corresponding to the Cs_low and the color signal ratios Cs_R1 and Cs_R2 obtained by the equation (4), and the original signal value C′_high of the saturated pixel according to the predetermined equation (5). , C′_middle, C′_low are calculated.

C′_high = C_low × Cs_R1
C′_middle = C_low × Cs_R2
C′_low = C_low (5)

  Then, the saturation signal evaluation unit 305 substitutes the calculated signal values C′_high, C′_middle, C′_low into the color signals corresponding to the original signals R_sat, G_sat, B_sat of the saturated pixels, and after the substitution The color signal is output to the shine correction amount adjustment unit 306.

  In the next S407, the shine correction amount adjustment unit 306 receives the input color signals R, G, B, the reference shine correction amounts Rh, Gh, Bh calculated in S404, and the saturated pixel calculated in S406. The original signal values R_sat, G_sat, and B_sat are acquired. Then, the shine correction amount adjustment unit 306 changes the reference shine correction amounts Rh, Gh, and Bh so that the input color signals R, G, and B have the color balance of the signal values R_sat, G_sat, and B_sat after the shine correction. Adjustment is performed to generate adjusted shine correction amounts Rh ′, Gh ′, and Bh ′.

  More specifically, the shine correction amount adjustment unit 306 sets a color signal corresponding to C_low having a low signal value among C_high, C_middle, and C_low used in the saturation signal evaluation unit 305 as a reference color signal. Here, a case where the B color signal is used as a reference will be described. The shine correction amount adjustment unit 306 sets a coefficient αY for changing the adjustment amount for the shine correction amount according to the level (luminance level) of the luminance signal Y input from the luminance signal generation unit 301. The value range of the coefficient αY is 0 to 1, and has the characteristics shown in FIG. The horizontal axis in FIG. 5 represents the luminance level of the luminance signal Y, and the vertical axis represents the coefficient αY (that is, gain). The threshold value Th_start in FIG. 5 represents a luminance value at which any one of the color signals R, G, and B in the subject area starts to be saturated, and the threshold value Th_end is a luminance at which all the color signals R, G, and B are saturated. Represents a value. Then, the shine correction amount adjusting unit 306 performs a calculation of a predetermined formula (6) in which the signal value B_sat is subtracted from the original signal value R_sat or G_sat and multiplied by the coefficient αY, whereby the difference value between the respective color signals is obtained. Signal values Rh ′ and Gh ′ that maintain a certain ratio are calculated.

(R−Rh ′) − (B−Bh) = αY × (R_Sat−B_sat)
(G−Gh ′) − (B−Bh) = αY × (G_Sat−B_sat) (6)

In this way, in Equation (6), the value obtained by subtracting B_sat from the original signal values R_sat and G_sat is multiplied by the coefficient αY having a range of 0 to 1. In other words, the shine correction amount adjustment unit 306 adjusts the reference shine correction amount so that the difference value between the corrected color signal values is smaller than the difference value between the original color signal values. .
Since the signal value Bh ′ is a reference color signal, the value of Bh is substituted as it is. Here, the B color signal has been described as a reference, but an R color signal or a G color signal may be used as a reference.

  In next step S408, the shine correction amount adjustment unit 306 outputs the adjusted shine correction amounts Rh ′, Gh ′, and Bh ′ calculated as described above to the shine correction processing unit 204 in FIG. That is, the adjusted correction amounts Rh ′, Gh ′, Bh ′ are input to the defect correction processing unit 204 as the defect correction amounts Rh_out, Gh_out, Bh_out. Accordingly, the shine correction processing unit 204 performs the shine correction process as described above using the shine correction amounts Rh_out, Gh_out, Bh_out, that is, the adjusted shine correction amounts Rh ′, Gh ′, Bh ′. .

<Second Embodiment>
Hereinafter, the second embodiment will be described. The configuration and basic processing flow of the digital camera of the second embodiment are the same as those of the first embodiment described above. In the first embodiment described above, the original signal value of the saturated pixel is calculated (estimated) in S406 of FIG. 4 using Equations (4) and (5), but in the second embodiment, the saturation pixel of the saturated pixel is calculated. The original signal value is obtained by a method different from that in the first embodiment. Hereinafter, in the second embodiment, processing different from that of the first embodiment will be described.

  In the second embodiment, when there is only one saturated color signal among the color signals R, G, and B of the target pixel determined as the saturated pixel in the saturated pixel determination in S405 of FIG. The evaluation unit 305 calculates the original signal value of the saturated pixel as described below.

  In the case of the second embodiment, the saturation signal evaluation unit 305 first uses the correction target color signals Rs, Gs, and Bs acquired by the correction target color acquisition unit 303 as signal levels as in the first embodiment described above. Cs_high, Cs_middle, and Cs_low in descending order. Then, the saturation signal evaluation unit 305 calculates the color difference signals Cs_sub1, Cs_sub2 and the color difference ratio Cs_subR according to a predetermined formula (7).

Cs_sub1 = Cs_high-Cs_low
Cs_sub2 = Cs_middle-Cs_low
Cs_subR = Cs_sub1 / Cs_sub2 (7)

  That is, in Expression (7), the difference value Cs_sub1, Cs_sub2 between the color signal value Cs_low whose signal value is the smallest and not saturated and the other color signal values Cs_high, Cs_middle, and the ratio Cs_subR of these difference values are calculated. .

  Next, the saturation signal evaluation unit 305 calculates the original signal value of the saturation pixel based on the color difference signals Cs_sub1, Cs_sub2 and the color difference ratio Cs_subR. For example, among the input color signals R, G, and B, color signals corresponding to the respective colors of Cs_high, Cs_middle, and Cs_low described above are C_high, C_middle, and C_low. Here, when there is one saturated color signal among the color signals R, G, and B of the saturated pixels, the above-described determination signals Is_R_sat, Is_G_sat, and Is_B_sat by the saturated pixel determination unit 302 are any one of the color signals. The signal indicates that it is saturated. Further, when any one color signal is saturated in the saturated pixel, the saturated color signal is C_high having the highest signal value, and the remaining C_middle and C_low color signals are not saturated. . For this reason, in the case of the second embodiment, the saturation signal evaluation unit 305 calculates the original signal values C′_high, C′_middle, and C′_low of the saturated pixels according to the predetermined equation (8).

C′_high−C_low = Cs_subR × (C_middle−C_low)
C'_middle = C_middle
C′_low = C_low (8)

  That is, in Expression (8), the original signal values C′_high, C′_middle, C′_low of the saturated pixels are obtained using the difference value ratio Cs_subR and the non-saturated color signal values Cs_low, C_middle. .

  Then, the saturation signal evaluation unit 305 substitutes C′_high, C′_middle, C′_low calculated by Expression (8) for the color signals corresponding to the original signals R_sat, G_sat, B_sat of the saturated pixels, The result is output to the shine correction amount adjustment unit 306. The subsequent processing is the same as in the first embodiment described above. According to the second embodiment, when there is only one saturated color signal among the color signals R, G, and B of the saturated pixel, the saturation pixel is detected by a method different from the example of the first embodiment. The original signal value can be calculated.

  As described above, in the first and second embodiments, for a saturated pixel in which at least one of the input color signals R, G, and B is saturated, the original color signal of the saturated pixel The amount of complementary color is adjusted based on the balance. According to the present embodiment, when a subject such as a person is photographed, even if a high-brightness saturated region occurs in the subject region, the brightness of the high-brightness saturated region is lowered to suppress saturation and color balance is reduced. An image corrected to the target subject color can be obtained without causing a coloring phenomenon due to collapse.

<Other embodiments>
As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.
In the above-described embodiment, an example in which the predetermined subject area is a human face area (skin color area) and the shine correction process is performed on the face area is described, but the present invention is limited to the lip correction of the face area. Not. As an example, the present embodiment can be applied to correction of shine on a high-luminance saturated region such as a body of an automobile. In this example, the amount of shine correction that is the correction target is obtained from the subject area of the car based on the body color and brightness, the saturated pixel in the subject area is determined, and the adjustment amount is calculated from the saturated pixel as described above. Obtaining and correcting the shine correction amount, determining the final shine correction amount and performing the shine correction.

  The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in the computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

  The above-described embodiments are merely examples of implementation in carrying out the present invention, and the technical scope of the present invention should not be construed as being limited thereto. That is, the present invention can be implemented in various forms without departing from the technical idea or the main features thereof.

  104: image processing unit, 105: face detection unit, 107: control unit, 203: shine correction amount determination unit, 204: shine correction processing unit, 301: luminance signal generation unit, 302: saturated pixel determination unit, 303: correction target Color acquisition unit, 304: shine correction amount calculation unit, 305: saturation signal evaluation unit, 306: shine correction amount adjustment unit

Claims (16)

Detecting means for detecting a saturated region in which the color signal value is saturated in a predetermined subject region of the input image;
A calculation means for calculating a color balance of the original color signal value in the saturation region when there is no upper limit for saturation of the color signal value;
Generating means for generating a correction amount in which the color balance of the corrected color signal value with respect to the saturation region becomes the color balance of the original color signal value;
Correction means for correcting the image signal of the saturation region based on the generated correction amount;
An image processing apparatus comprising:   The image processing apparatus according to claim 1, wherein the detection unit detects the saturated region in which at least one color signal is saturated among a plurality of color signals that determine a color.   3. The calculation unit according to claim 1, wherein the calculation unit calculates a color balance of the original color signal value of the saturation region based on a color balance of a color signal value of the predetermined subject region. 4. Image processing device.   The said calculation means calculates the said original color signal value of the said saturation area | region, and calculates the color balance of the said original color signal value, The any one of Claim 1 to 3 characterized by the above-mentioned. Image processing device.   The calculation means calculates a color balance of the original color signal value of the saturated region based on a color signal ratio of the predetermined subject region and a color signal value that is not saturated of the predetermined subject region. The image processing apparatus according to claim 1, wherein:   The calculation means calculates a signal ratio between the color signal value having the smallest color signal value and the other color signal values among the color signal values of the predetermined subject region as the color signal ratio, and the color signal value The image processing apparatus according to claim 5, wherein a color balance of an original color signal value in the saturation region is calculated using a color signal value having the smallest color signal value as the color signal value that is not saturated.   The calculating means calculates a color balance of the original color signal value based on the difference value of the color signal of the predetermined subject area and the color signal value of the predetermined subject area that is not saturated. The image processing apparatus according to claim 1, wherein the image processing apparatus is characterized.   When the saturated color signal value of the predetermined subject area is a single color signal value, the calculating means has the smallest color signal value among the color signal values of the predetermined subject area. The difference between each color signal value and the other color signal values is calculated as a difference value between the color signals, and a ratio between the color signal difference values is calculated, and the difference value ratio and the non-saturated color signal value are calculated. The image processing apparatus according to claim 7, wherein a color balance of an original color signal value in the saturation region is calculated using The generating means includes
Obtaining means for obtaining a correction target color from an image signal of the predetermined subject area;
Correction amount calculation means for calculating a reference correction amount based on the image signal of the predetermined subject area and the correction target color;
Adjusting means for adjusting the reference correction amount so that the color balance of the color signal value after correction by the correction means becomes the color balance of the original color signal value;
The image processing apparatus according to claim 1, wherein the correction amount after the adjustment is set as the correction amount for the image signal in the saturation region.   The adjustment unit adjusts the reference correction amount so that a difference value between color signals after correction by the correction unit is smaller than a difference value in the original color signal value. Item 10. The image processing apparatus according to Item 9.   The adjusting means uses the signal value obtained by multiplying a difference value between a color signal used as a reference among the original color signals and another color signal by a predetermined coefficient having a value range of 0 to 1. The image processing apparatus according to claim 10, wherein the correction amount is adjusted. The correction amount calculation means calculates a color having a reverse characteristic of the correction target color as the reference correction amount,
12. The correction unit according to claim 9, wherein the correction unit performs the correction by subtracting a correction amount after the adjustment is performed from a color signal value of an image signal in the saturation region. Image processing apparatus according to   The image processing apparatus according to claim 1, wherein the color signal includes three color signals of three primary colors.   The image processing apparatus according to claim 1, wherein the detection unit detects the saturation region in a human face region that is the predetermined subject region. A detection step of detecting a saturated region in which the color signal value is saturated in a predetermined subject region of the input image;
A calculation step of calculating a color balance of the original color signal value in the saturation region when there is no upper limit for saturation of the color signal value;
A generation step of generating a correction amount in which the color balance of the color signal value after correction with respect to the saturation region becomes the color balance of the original color signal value;
Based on the generated correction amount, a correction step of correcting the image signal of the saturation region,
An image processing method for an image processing apparatus, comprising:   The program for functioning a computer as each means of the image processing apparatus of any one of Claim 1 to 14.

Images