JP4385964B2 - Photo image processing method and photo image processing apparatus - Google Patents

Description

  In the present invention, for example, R (red), G (green), B (blue) (hereinafter referred to as “RGB”) can be reproduced for color image data obtained by reading a photographic film such as a negative film. In detail, a predetermined average value is obtained for each color component of the pixels constituting the original image data, and the average value corresponds to gray. The present invention relates to a photographic image processing method and a photographic image processing apparatus that correct color components of each pixel so as to have a predetermined value.

  2. Description of the Related Art Conventionally, as a photographic image processing method for printing an image recorded on a negative film on a photographic paper having a good color tone, a LATD (Large Area Transmission Density) exposure method based on Evans's theorem is known. This exposure method is based on Evans's theory that the average outdoor subject will become gray when the colors of the negatives are mixed together. The exposure is performed by adjusting each RGB exposure amount so that the light is reproduced in gray on the photographic paper. Specifically, the negative film is irradiated with light, and the transmitted light is read by the image sensor. Color image data is generated, an average value of the color image data is calculated and derived for each RGB of each pixel, and an analog photo printer adjusts so that each RGB average value becomes a predetermined value corresponding to gray. The photographic paper is exposed by adjusting the optical filter, and the exposure amount from each of the RGB light sources is adjusted in the digital photographic printer.

According to the above-described conventional photographic image processing method, there is a problem that an overcorrected photographic print is output due to the color deviation of the subject (person, background). For example, in the case of a scene where a person is photographed against a lawn, the lawn area is finished in gray, while magenta, which is a complementary color of the lawn, appears strongly in the person area. Such a situation is called color failure. As a countermeasure, high saturation pixels are removed in the LATD exposure method, or the color correction rate for the feature color occupying the largest area is made different from the color correction rate for the background color other than the feature color. A method of correcting the error has been proposed.
JP 2000-330221 A

  However, even with the method of removing the high saturation pixels described above, if the colored region is large in the low saturation image, most of the image becomes relatively high saturation. Even if the pixel is corrected, sufficient correction cannot be performed, and when correcting based on a small amount of pixel data by adjusting a threshold value for removing a high saturation pixel, there is a problem that appropriate correction becomes difficult. It was not perfect and there was room for further improvement.

  In view of the above-mentioned conventional drawbacks, the present invention more effectively eliminates the occurrence of color feria due to low-saturation pixels, which are wide colored areas, while reliably removing the effects of high-saturation pixels. The object is to provide a photographic image processing method and apparatus capable of obtaining a close color image.

In order to achieve the above-mentioned object, the first characteristic configuration of the photographic image processing method according to the present invention is, as described in claim 1 of the claims, for each color component of the pixels constituting the original image data. A photographic image processing method for obtaining a predetermined average value and correcting the color component of each pixel so that the average value becomes a predetermined value corresponding to gray, wherein the saturation of each pixel constituting the original image data is determined A saturation calculation step for obtaining a distance from the brightness axis of each pixel position in the Munsell color system color solid, and a lower saturation pixel weighting a pixel on a lower saturation side than a preset saturation threshold A weighting factor derivation step for obtaining a weighting factor that correlates with the saturation of each pixel so that the factor becomes large for each pixel, and a ratio of the sum of the weighting factor to the number of pixels for which the summation of the weighting factor is to be calculated but Irodorido閾 to satisfy a predetermined ratio By adjusting a certain weight factor adjusting step of adjusting the weighting factors, a point consisting of the pixel data correction step of correcting the color components of each pixel based on the weighting coefficients calculated.

  According to the above-described configuration, an image in which a large colored region with low saturation exists (obtained) is obtained by adjusting the ratio of the total number of weighting factors and the corresponding number of pixels to satisfy a predetermined ratio. Even if the ratio of the number of pixels corresponding to the sum of the weighted coefficients is different from the predetermined ratio), the color can be corrected by considering the weighting condition depending on the saturation. It is possible to effectively suppress the occurrence of feria and obtain a more natural color image.

  In the second feature configuration, as described in claim 2, in addition to the first feature configuration described above, the pixel data correction step calculates a product sum of each color component for each pixel and the weight coefficient as the weight. A weight average value calculating step for obtaining a weight average value for each color component divided by the sum of the coefficients is provided, and the color component of each pixel is corrected based on the weight average value for each color component.

  According to the above-described configuration, by correcting the color component of each pixel based on the weighted average value for each color component, it is possible to reliably perform the correction in consideration of the weighting condition according to the saturation, and the occurrence of color failure It is possible to obtain a color image closer to nature by effectively suppressing the above.

  In the third feature configuration, as described in claim 3, in addition to the first or second feature configuration described above, the sum of the weighting factor and the weighting factor is a low value that is equal to or less than a saturation threshold of a predetermined range. This is the point required for chroma pixels.

  According to the above-described configuration, it is possible to remove the high-saturation pixels having a large influence and to correct the weighted condition in consideration of the saturation even if the image includes a large colored region with low saturation. It is possible to effectively suppress the occurrence of color feria and obtain a more natural color image.

  In the fourth feature configuration, as described in claim 4, in addition to any of the first to third feature configurations described above, the weighting factor is a linear function p · (Sa for the saturation Sa. ) (P is a constant), and the value of the constant p is adjusted.

  According to the above-described configuration, the threshold value of the high saturation pixel to be removed can be variably adjusted by setting the weighting coefficient based on the saturation by a simple method of adjusting the linear coefficient. This makes it possible to obtain a color image that is closer to nature.

In the fifth feature configuration, as described in claim 5, in addition to any of the first to third feature configurations described above, the weighting coefficient is a power function q · (Sa for the saturation Sa. ) Is obtained based on ^γ (q is a constant), and the value of the power γ is adjusted.

  According to the above-described configuration, the weighting factor of the low saturation pixel can be set larger and the weighting factor of the high saturation pixel can be set smaller than when the weighting factor is obtained in proportion to the saturation of each pixel. Since the weight average value for each color component with respect to all the pixels is obtained based on such a weight coefficient and the LATD process is performed, the color balance can be adjusted more effectively suppressing the occurrence of color feria. is there.

  The sixth feature configuration is that, as described in claim 6, in addition to any of the first to fifth feature configurations described above, the weighting factor is set according to the hue.

  According to the above-described configuration, the weighting coefficient obtained according to the saturation of the pixel can be variably set according to the hue of the pixel. This makes it possible to adjust to a more natural color balance. For example, a yellow color tone is a color tone often found in artifacts, and in order to correct such a yellow pixel to an original color, it is necessary to set a weighting factor larger than that of other hue pixels. In a photographed image with a background of light, it is necessary to set a weighting coefficient smaller than pixels of other hues in order to suppress the occurrence of color feria even in a portion where the light is not exposed and the saturation is low. Even in such a case, the weight coefficient can be set appropriately.

The first characteristic configuration of the photographic image processing apparatus according to the present invention is to calculate a predetermined average value for each color component of the pixels constituting the original image data, as described in claim 7 of the claims. A photographic image processing apparatus that corrects the color component of each pixel so that an average value becomes a predetermined value corresponding to gray, and the saturation of each pixel constituting the original image data is represented by a Munsell color system color solid And a saturation calculation unit for obtaining the distance from the lightness axis of each pixel position in each of the pixels, and for each pixel on the lower saturation side than a preset saturation threshold, the weighting factor increases for each lower saturation pixel A weighting factor deriving unit that obtains a weighting factor that correlates with the saturation of the pixel for each pixel, and a ratio of the sum of the weighting factor to the number of pixels for which the summation of the weighting factor is calculated satisfies a predetermined ratio. by adjusting the saturation threshold, adjusting the weighting factor A weight coefficient adjusting unit that lies in comprising a pixel data correcting section for correcting the color components of each pixel based on the weighting coefficients calculated.

  In the second feature configuration, in addition to the first feature configuration described above, the pixel data correction unit may calculate the product sum of each color component and the weight coefficient for each pixel as the weight. A weight average value calculation unit for obtaining a weight average value for each color component divided by the sum of the coefficients is provided, and the color component of each pixel is corrected based on the weight average value for each color component.

  In the third feature configuration, as described in claim 9, in addition to the first or second feature configuration described above, the sum of the weighting factor and the weighting factor is a low value that is equal to or lower than a saturation threshold of a predetermined range. This is the point required for chroma pixels.

  As described above, according to the present invention, it is more natural to effectively eliminate the occurrence of color feria due to low saturation pixels, which is a wide coloring area, while reliably removing the influence of high saturation pixels. It has become possible to provide a photographic image processing method and apparatus capable of obtaining a close color image.

  Embodiments of a photographic image processing method and a photographic image processing apparatus according to the present invention will be described below. As shown in FIG. 1, a photographic image processing apparatus 1 includes a photographic printer 2 that performs an exposure process based on output image data on a photographic paper P and develops the exposed photographic paper, and a developed photographic film. A media driver 32 that reads image data from an image data storage medium M such as a memory card that stores image data taken by a film scanner 31 or a digital still camera that reads an image from F, or a general-purpose computer as a controller 33 The print station is configured to include input of print order information for a photographic image as an input original image and an operation station 3 for performing various image correction processes. The print is edited from the original image by the operation station 3. Data is output to the photographic printer 2 so that a desired photographic print can be made. It is made.

  As shown in FIGS. 1 and 2, the photographic printer 2 has two systems of photographic paper magazines 21 containing roll-shaped photographic paper P, and photographic paper P drawn from the photographic paper magazine 21 with a predetermined print. A sheet cutter 22 that cuts into a size; a back print unit 23 that prints print information such as a frame number on the back of the cut photographic paper P; an exposure unit 24 that exposes the photographic paper P based on the print data; A development processing unit 25 including a plurality of processing tanks 25a, 25b, and 25c filled with processing solutions for developing, bleaching, and fixing the exposed photographic paper P is disposed along the transport path of the photographic paper P. The laterally-feeding conveyor 26 that discharges the photographic paper P that has been dried after the development process, and the sheet-paper (photo print) P that is stacked on the laterally-feeding conveyor 26 is sorted in order units. Configured to include the data 27.

  The exposure unit 24 receives the RGB three-color light flux modulated on the basis of the print data in the main scanning direction orthogonal to the conveyance direction with respect to the photographic paper P conveyed in the sub-scanning direction by the conveyance mechanism 28. An exposure head 24a for outputting and exposing is accommodated.

  A transport mechanism 28 including a plurality of roller pairs that transport the photographic printing paper P at a process speed corresponding to the exposure unit 24 and the development processing unit 25 disposed along the transport path is disposed before and after the exposure unit 24. Is provided with a chucker-type transport mechanism 28a capable of transporting photographic paper P in multiple rows.

  The controller 33 provided in the operation station 3 is installed with an application program that operates under the control of a general-purpose operating system and executes various controls of the photographic processing apparatus 1, and a monitor 34 as an operation interface with the operator. A keyboard 35, a mouse 36, and the like are connected.

  The photographic processing process executed by the cooperation of the hardware and software of the controller 33 will be described in functional blocks. As shown in FIG. 3, a photographic image as an original image read by the film scanner 31 or the media driver 32 is shown. The image input unit 40 that performs predetermined preprocessing and transfers it to the memory 41 (to be described later), and print order information and image editing information are displayed on the screen of the monitor 34, and necessary data input for these is displayed. A graphic user interface unit 42 for generating various control commands based on an input operation from the keyboard 35 or mouse 36 for the displayed graphic operation screen; Source transferred from the image input unit 40 Generates print order information and a memory 41 in which image data, corrected image data after correction processing by an image processing unit 47 described later, processing parameters at that time, and set print order information are partitioned and stored. From the order processing unit 43, the image processing unit 47 that performs various corrections such as gradation correction, color correction, enlargement / reduction processing, distortion correction on the original image stored in the memory 41, and the graphic user interface unit 42 A display control unit 46 including a video RAM for displaying the original image and the corrected image data developed in the memory 41 based on the display command, and various input / output graphic data on the monitor 34; Print data for outputting the final corrected image for which various correction processes have been completed to the photographic printer 2 is generated. A lint data generating unit 44, and the like formatter 45 which converts the final corrected image according to customer orders to a file format for writing in a storage medium such as a CD-R.

  The film scanner 31 is configured to operate in two modes: a pre-scan mode that reads an image recorded on the film F at a high speed although it has a low resolution, and a main scan mode that reads a high-resolution image at a low speed. Various correction processes described later are performed on the low-resolution image read in the can mode, and the high-resolution image read in the main scan mode based on the correction parameters stored in the memory 41 at that time. The final correction process is executed. Similarly, the image file read from the media driver 32 includes a high-resolution captured image and its thumbnail image, and various correction processes described later are performed on the thumbnail image. Based on the stored correction parameters, a final correction process is performed on the high-resolution captured image. When the image file does not include a thumbnail image, the image input unit 40 generates a thumbnail image from the high-resolution captured image and transfers it to the memory 41. In this way, the calculation load of the controller 33 is reduced by executing various editing processes that are frequently trial and error on low-resolution images.

  The image processing unit 47 is suitable for, for example, a distortion correction unit 50 that corrects distortion caused by a photographing lens with respect to an original image, for example, a sharpening processing unit 51 that enhances an edge of an image and reduces noise, and is suitable for the size of a photographic print. An enlargement / reduction processing unit 52 for converting to an image size, a color correction unit 53 for adjusting a color balance so that natural colors can be reproduced, and the like.

  The color correction unit 53 includes a saturation calculation unit 54 for obtaining saturation for each pixel constituting the original image data, and a weight for obtaining a weighting coefficient correlated with each obtained saturation for each pixel. A coefficient deriving unit 55, a weighting factor adjusting unit 56 that adjusts the weighting factor so that the ratio of the obtained sum of the weighting factors and the number of corresponding pixels satisfies a predetermined ratio, and each color component for each pixel and the weighting factor A weighted average value calculating unit 57 for obtaining a weighted average value for each color component obtained by dividing the product sum by the sum of the weighting coefficients, and a pixel data correcting unit for correcting the color component of each pixel based on the weighted average value for each color component 58.

  The saturation calculation unit 54 is configured to create a preview image reduced to a predetermined number of pixels from the frame image so as to adapt to the calculation described later, and calculate the saturation Sa (i) for each pixel. . Here, i indicates the number of the pixel, and i = 0, 1, 2,..., N−1 (n: the number of pixels). For example, in the case of a low-resolution image such as a thumbnail image or an image read in the pre-scan mode, the preview image may be used at the same magnification.

  The weighting factor deriving unit 55 is configured to obtain a weighting factor Sb (i) correlated with each saturation Sa (i) obtained by the saturation calculating unit 54 for each pixel. The weighting factor Sb (i) changes linearly with respect to the saturation Sa (i) so that the correction strength Rc (i) becomes stronger as the saturation pixel becomes lower, for example, as shown in FIG. It is calculated on the basis of the correction intensity characteristic to be corrected or the correction intensity characteristic that changes exponentially with respect to the saturation Sa (i). For example, the weight coefficient Sb (i) can be obtained by a calculation formula shown in (Expression 1) or (Expression 2).

Here, the saturation Sa (i) is expressed by the distance from the center, with hues arranged along the circumference as shown in FIG. In the color solid in the Munsell color system, it is obtained as the distance from the center when the RGB color component of each pixel is plotted on the cross section with the center of the brightness axis shown in FIG. Is a saturation threshold set for each hue. In other words, (Equation 1) indicates that, in a pixel where the saturation Sa (i) is equal to or less than the saturation threshold value Sath, the linear function p · (Sa (i) based on the saturation threshold value Sath is used as the weight coefficient Sb (i). )) (P is a constant), the weighting coefficient Sb (i) is increased as the saturation Sa (i) is lower, and conversely, the weighting coefficient is increased as the saturation Sa (i) is higher. This indicates that Sb (i) is calculated to be small, and that the weighting coefficient Sb (i) is set to 0 in a pixel where the saturation Sa (i) is larger than the saturation threshold Sath. . Similarly, in (Equation 2), in the pixel in which the saturation Sa (i) is equal to or less than the saturation threshold value Sath, the power function q · (Sa () () is based on the weight coefficient Sb (i) based on the saturation threshold value Sath. i)) By calculating based on ^γ (q is a constant), the lower the saturation Sa (i), the larger the weight coefficient Sb (i), and conversely, the higher the saturation Sa (i), Indicates that the weighting coefficient Sb (i) is calculated to be small, and indicates that the weighting coefficient Sb (i) is set to 0 in a pixel where the saturation Sa (i) is greater than the saturation threshold Sath. It is. Here, when the weight coefficient Sb (i) is 0, it is removed from the target of weight average value calculation described later as a high saturation pixel.

  As shown in FIG. 4B, the saturation threshold value Sath is set for each region (hue) by dividing the region by hue in the Munsell color solid sectional view. In other words, the hue indicated by each pixel of the original image data is applied to the hue area in the Munsell color cube, and the weight coefficient Sb is calculated using the correction intensity Rc (i) calculated using the saturation threshold Sath in the hue area. With the configuration for calculating (i), the weighting coefficient Sb (i) is set according to the hue. The saturation threshold value Sath is a threshold value that takes a value in a predetermined range for removing the high saturation pixel from the correction target image, and is a value for preventing the occurrence of color failure due to the influence of the high saturation pixel.

  In addition, when the display color of the original image has a color deviation, it is emphasized so that many pixels of a specific hue that cause the color deviation are included, so that the color can be obtained by a LATD process performed later. It is possible to easily remove the bias. For example, many artifacts have a yellow color tone, and the captured image under tungsten light is generally yellowish. Therefore, in order to correct such a yellow pixel to the original color, other weighting factors are used. It is necessary to set a larger pixel than the pixel of the hue, and even if the photographed image with the plant background is not exposed to light and has a low saturation, the weight coefficient is set to a pixel of another hue to suppress the occurrence of color feria. Must be set smaller than In such a case, the saturation threshold value Sath can be adjusted to an appropriate weighting factor by setting it large in the yellow region and small in the green region.

  In the above (Equation 1), by setting the constant p based on the saturation threshold value Sath, the linear function is a linear function based on the saturation threshold value Sath. However, the present invention is not limited to this. A linear function can be set as appropriate. Further, in the above (Equation 2), the constant function q is set based on the saturation threshold value Sath to set the power function based on the saturation threshold value Sath. However, the present invention is not limited to this. A function that should be appropriate can be set.

  In addition, the saturation threshold value Sath is set to a range such that the saturation threshold value Sath effectively acts on a low saturation pixel equal to or lower than the saturation threshold value of the predetermined range, whereby a high saturation pixel in which color failure may occur. Can also be effectively removed.

Further, the saturation threshold value Sath is set as a fixed value to remove a predetermined high saturation pixel region, the coefficient p in (Equation 1) is set as p = 1 / (Sath + c), and the value of c is changed. The coefficient q in (Equation 2) may be set as q = (1 / (Sath + c)) ^γ, and the value of c may be varied.

  The weighted average value calculator 57 calculates the product sum rx, gx, bx of each color component r (i), g (i), b (i) and the weighting coefficient Sb (i) for each pixel as the weighting coefficient Sb. Weight average values rxa, gxa, bxa for each color component divided by the sum nx of (i) are obtained, and are calculated by the calculation formulas shown in (Equation 3) and (Equation 4).

The weight coefficient adjusting unit 56 makes a correction intensity ratio Ra, which is a ratio of the sum nx of the weight coefficient Sb (i) to the number n of pixels to be calculated of the sum nx of the weight coefficient Sb (i) , satisfy a predetermined ratio. When the correction intensity ratio Ra does not satisfy a predetermined ratio, the constant p in the linear function p · (Sa (i)) (p is a constant) or the power function q (Sa (i)) The constant q or the power number γ in ^γ (q is a constant) is adjusted. That is, as shown in FIGS. 6A, 6B, and 6C, the correction strength characteristic is changed by adjusting the constants p , q or the power number γ, and the weight coefficient deriving unit 55 or the The weighted average calculation unit 57 performs the series of calculations described above. The number of pixels to be calculated is the number of pixels used for obtaining the sum nx of the weighting factors Sb (i), that is, the number of pixels n of the preview image, and the correction intensity ratio Ra has been set so far. From the experimental results, it is preferable that the value is about 0.5 or more. However , the number of pixels to be calculated is not limited to the number of pixels n of the image. For example , if the number of pixels in the low saturation region is set, the influence of color feria is reduced in the region recognized as the low saturation region. It can be effectively suppressed and higher-definition color expression becomes possible. Further, the adjustment of the constant p can be performed by adjusting the saturation threshold value Sath, for example, if the constant p is a value based on the saturation threshold value Sath.

The pixel data correction unit 58 performs LATD processing based on the weight average values rxa, gxa, bxa for each color component calculated by the weight average value calculation unit 57 when the correction intensity ratio Ra satisfies a predetermined ratio. For example, the R component correction value Δrxa is obtained using the G component as a reference, the B component correction value Δbxa is obtained using the G component as a reference, respectively, and Δrxa is obtained for the R component of each pixel. Correction is performed by adding Δ b xa to the B component of each pixel.

  Hereinafter, the operation of deriving the weighted average values rxa, gxa, and bxa for each color component by the color correction unit 53 will be described based on the flowchart shown in FIG. When the saturation calculation unit 54 creates a preview image having a predetermined number of pixels, for example, 640 × 480 pixels from the image stored in the memory (S1), and stores the number of pixels n = 640 × 480 of the image (S2). Each block of the color correction unit 53 has a product sum rx, gx, bx of each data, for example, each color component r (i), g (i), b (i) and the weight coefficient Sb (i). A storage area such as the sum nx of the weighting factors Sb (i) is initialized (S3). Further, the color correction unit 53 resets the internal count value i for counting the pixels in order to calculate all the pixels of the image (S4).

  The saturation calculator 54 calculates the saturation Sa (i) from the color components r (i), g (i), and b (i) of the pixel corresponding to the count value i (S5).

  The weight coefficient adjustment unit 56 selects a saturation threshold value Sath having a higher priority from the saturation threshold values given as initial values (S6).

  The weighting factor deriving unit 55 calculates the ratio between the saturation Sa (i) and the saturation threshold Sath (S7), and if it is 1.0 or less, the correction strength Rc (i) is set to, for example, the linear It is calculated by a function (S8). If it is larger than 1.0, it is set to 1.0 (S9). Next, a weighting coefficient Sb (i) is calculated using the correction strength Rc (i) (S10).

  The weighted average calculation unit 56 integrates each color component r (i), g (i), b (i) of the pixel and the weight coefficient Sb (i), and each color component r (i), g of the other pixel. (I) By adding to the integrated value obtained by b (i) and the weighting coefficient Sb (i), the product-sum values bx, gx, rx are updated, and the weighting coefficient Sb (i) is changed to another value. Nx is updated by adding to the weight coefficient Sb (i) in the pixel (S11).

  When the color correction unit 53 increments the internal counter value i (S12) and the above calculation is completed for all the pixel numbers (S13), the weight coefficient adjustment unit 56 causes the correction intensity ratio Ra to be corrected. Is confirmed (S14). When the correction intensity ratio Ra is less than the predetermined ratio, the above-described steps S3 to S14 are performed again under the condition that the saturation threshold value Sath different from the saturation threshold value Sath is selected in step S6. If the predetermined ratio is satisfied, the weighted average calculation unit 56 calculates the weighted average values rxa, gxa, bxa according to (Equation 3) (S15).

  Note that the above-described flowchart showing the photographic image processing method is merely an example, and it is not always necessary to execute this procedure faithfully.

  In the above-described embodiment, the saturation threshold value Sath is set to a different value for each hue. However, the present invention is not limited to this, and may be set to a uniform value.

  In the above description, the weight average value of the image is calculated using one piece of image data, and the LATD process is performed based on the weight average value. However, the weight average value calculated using a plurality of pieces of image data is described. It is good also as a structure which performs LATD processing based on this.

  In the above description, pixel data correction is performed by obtaining a weighted average value for each color component obtained by dividing the product sum of the color component for each pixel and the weighting factor by the sum of the weighting factors, and based on the weighted average value for each color component. In the above description, the color component of each pixel is corrected. However, the present invention is not limited to this, and the color component of each pixel may be corrected based on the weighting factor.

  FIG. 8 shows the result of LATD processing performed on the photographic image shown in FIG. 8A based on the weighted average value obtained by the arithmetic processing of (Equation 1), (Equation 3), and (Equation 4) described above. FIG. 8C shows the result of performing the LATD processing using the correction value obtained by the method of simply removing the high saturation pixels as shown in FIG. 8B.

  As a result, in the conventional LATD processing, a high saturation image area, for example, a low saturation image in other image areas excluding an empty image area, a relatively high saturation image area, for example, a soil image. Due to the influence of the area, an image area having a lower saturation, for example, an asphalt image area, has a soil color, so that it is confirmed that a color failure has occurred. On the other hand, in the method according to the present invention, since the color of asphalt is correctly expressed, it can be confirmed that the color feria is improved.

External view of photographic image processing device Internal explanatory diagram of photographic image processing device Functional block diagram of photographic image processing device It is explanatory drawing of the color cube of Munsell, (a) is a general view, (b) is sectional drawing for demonstrating the example of a hue area | region. Illustration of saturation-corrected intensity characteristics It is explanatory drawing of the change of saturation-correction intensity characteristic, (a) is explanatory drawing of the difference of the saturation-correction intensity characteristic when the saturation-correction intensity characteristic which changes linearly is changed by adjustment of the constant p , (B) is an explanatory diagram of the difference between saturation-correction intensity characteristics when the saturation-correction intensity characteristics that change exponentially are changed by adjusting the constant q, and (c) is correction that changes exponentially. Explanatory diagram of the difference between saturation and corrected intensity characteristics when the intensity characteristics are changed by adjusting the power γ Flowchart for explaining the procedure for deriving the weighted average value for each color component It is explanatory drawing of the photographic image processing result by this invention, (a) is an original image, (b) is an image by the photographic image processing using this invention, (c) is an image by the photographic image processing using a prior art.

1: Photo image processing device 47: Image processing unit 53: Color correction unit 54: Saturation calculation unit 55: Weight coefficient derivation unit 56: Weight coefficient adjustment unit 57: Weight average value calculation unit 58: Pixel data correction unit

Claims (9)

A photographic image processing method for obtaining a predetermined average value for each color component of pixels constituting original image data and correcting the color component of each pixel so that the average value becomes a predetermined value corresponding to gray,
A saturation calculation step for obtaining the saturation of each pixel constituting the original image data as a distance from the brightness axis of each pixel position in the Munsell color system color solid ;
A weighting factor that finds a weighting factor that correlates with the saturation of each pixel so that the weighting factor increases for lower saturation pixels than the preset saturation threshold. A derivation step;
A weighting factor adjustment step for adjusting the weighting factor by adjusting the saturation threshold so that the ratio of the summation of the weighting factors to the number of pixels to be calculated for the summation of the weighting factors satisfies a predetermined ratio;
A photographic image processing method comprising: a pixel data correction step for correcting a color component of each pixel based on a calculated weighting factor.   The pixel data correction step includes a weighted average value calculating step for obtaining a weighted average value for each color component obtained by dividing a product sum of each color component for each pixel and the weighting factor by a total sum of the weighting factors. The photographic image processing method according to claim 1, wherein the color component of each pixel is corrected based on the weighted average value.   The photographic image processing method according to claim 1 or 2, wherein the sum of the weighting coefficient and the weighting coefficient is obtained for a low saturation pixel that is equal to or less than a saturation threshold value in a predetermined range.   4. The photographic image according to claim 1, wherein the weighting factor is obtained based on a linear function p · (Sa) (p is a constant) with respect to the saturation Sa, and a value of the constant p is adjusted. 5. Processing method. The weighting factor is obtained based on a power function q · (Sa) ^γ (where q is a constant) with respect to the saturation Sa, and the value of the power number γ is adjusted. Photo image processing method.   6. The photographic image processing method according to claim 1, wherein the weighting factor is set according to a hue. A photographic image processing apparatus that obtains a predetermined average value for each color component of pixels constituting original image data and corrects the color component of each pixel so that the average value becomes a predetermined value corresponding to gray,
A saturation calculation unit that obtains the saturation of each pixel constituting the original image data as a distance from the brightness axis of each pixel position in the Munsell color system color solid ;
A weighting factor that finds a weighting factor that correlates with the saturation of each pixel so that the weighting factor increases for lower saturation pixels than the preset saturation threshold. A derivation unit;
A weighting factor adjustment unit that adjusts the weighting factor by adjusting the saturation threshold so that the ratio of the summation of the weighting factors to the number of pixels for which the sum of the weighting factors is to be calculated satisfies a predetermined ratio;
A photographic image processing apparatus comprising a pixel data correction unit that corrects a color component of each pixel based on a calculated weighting factor.   The pixel data correction unit includes a weighted average value calculating unit that obtains a weighted average value for each color component obtained by dividing the product sum of each color component for each pixel and the weighting factor by the sum of the weighting factors, The photographic image processing apparatus according to claim 7, wherein the color component of each pixel is corrected based on the weighted average value.   The photographic image processing apparatus according to claim 7 or 8, wherein the sum of the weighting coefficient and the weighting coefficient is obtained for a low saturation pixel that is equal to or less than a saturation threshold of a predetermined range.