JP2011109479A - Color control method, and image processing apparatus employing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that work for narrowing down a color tone control value with a subjective evaluation based determination while controlling a color tone of image output, that becomes a replica of an original picture, requires skills and much time and efforts and that, if a control amount is minute, a subjective comparison sense may be paralyzed and it may become impossible to rightly determine which one of a plurality of approximate replicas is closest to the original picture. <P>SOLUTION: Color tones of an original picture and a controlled image are easily and subjectively determined and inputted to an image processing apparatus. This result is made quantitative and distributed in a color space used for color tone control. From this distribution, coordinates of the center of gravity (coordinates of a point A that becomes a position of the center of gravity) are obtained and a control amount (dL*, da*, db*) corresponding to the coordinates is obtained as an optimal control amount. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a color adjustment method for adjusting the color tone of an output product or a monitor display color tone by a color printer or the like, and an image processing apparatus using the method.

  In recent years, image processing techniques using ink jet printers have become more sophisticated. Specifically, the size of ink droplets used for recording is smaller, the scanning method of the recording head is improved, and the ink itself is improved. With such high performance, the granularity and glossiness of images have improved, and it has become possible to realize high-quality images such as silver salt photographs.

  One market that requires such high-quality images is a market called fine art. In the fine art market, a digital art image created by a computer is recorded using the above-described ink jet printer technology. The recorded images are treated like paintings and traded as valuable works. Inkjet printers are also used for cultural property protection. Specifically, paintings as valuable cultural properties, replicas such as folding screens (replicas), etc., are exhibited and stored at museums and schools.

  Conventionally, as a method of creating this type of duplicate image, a high-quality digital camera is used to photograph the cultural asset that is the original image with high definition, and color adjustment is repeatedly performed on the captured data using image editing software. A method of outputting a duplicate image close to color by a printer has been used. Color tone adjustment using such image editing software often depends on the ability of the operator and requires advanced knowledge and skill. In the color tone adjustment, for example, the following steps are executed. That is: The duplicate image data is printed by a printer to generate a duplicate. 2. Compare the color difference between the original and the reproduction by subjective evaluation. 3. The direction and amount of color adjustment are estimated from the comparison result. 4). Apply the estimated adjustments to the output image data. 5. Print the adjusted output image data to generate a duplicate. And 6. Steps 2 to 5 are repeated until the color difference is sufficiently small.

  In such an iterative adjustment method, it is necessary to estimate a color adjustment direction and an adjustment amount based on subjective evaluation. This estimation requires experience and knowledge about color and skill, and is difficult for beginners and inexperienced workers. Furthermore, there is a problem that even a skilled person needs repetition and requires a lot of work.

  In order to cope with such a problem, a method called variation printing has been disclosed as a method for more easily adjusting the color tone. For example, in the variation print disclosed in Patent Document 1, the most preferable color tone can be easily obtained as the final output by reducing the original image to a predetermined size, changing the color tone in various ways, and performing layout printing on one sheet of paper. You can choose. In addition, the variation print disclosed in Patent Document 2 proposes a method capable of checking the color tone when the output is changed to various color tones with an image close to the final output. In any of these methods, a desired color tone is determined from the output result of the variation print in which the color tone of the image is variously changed.

JP-A-8-251393 JP 2007-316316 A

  However, the conventional method has the following problems.

  That is, when the color tone of the image is changed stepwise, if the adjustment step of the color tone adjustment is large, there is a high possibility that an intermediate color tone of a plurality of sample outputs becomes a desired color tone. In such a case, it is necessary to set a finer adjustment step near the desired color tone, output a plurality of samples, reconfirm the color tone, and narrow down to an appropriate adjustment value. As a result, multi-stage adjustment value setting and sample output are required, which requires much effort and time. In addition, a lot of paper and color materials (ink toner) are consumed.

  On the other hand, when changing the color tone of an image step by step, if the adjustment steps of the color tone adjustment are set finely from the beginning, a very large number of sample outputs must be performed. Or consumes a large amount of paper and color materials (ink and toner).

  In addition, while comparing the original image with the color adjustment sample many times visually, the subjective sense of comparison gradually paralyzes, making it impossible to correctly determine which of the approximated samples is closest to the original image. There is a sensory problem of coming. This is particularly noticeable when comparing a plurality of samples whose color tone is close to that of the original image, and often becomes a problem when finally narrowing down the color tone.

  The present invention has been made in view of the above-described conventional example, and an object thereof is to provide a color adjustment method in which anyone can easily perform color adjustment and an image processing apparatus to which the method is applied.

  In order to achieve the above object, the color adjustment method of the present invention has the following configuration.

  That is, a color adjustment method for adjusting the color tone of an output image image-processed by an image processing device, wherein the image processing device inputs image data of an original image of the output image to be color tone adjusted. A setting step for setting a plurality of adjustment candidate values for adjusting the color tone of the output image, and a plurality of adjustment candidates set in the setting step for the image data input in the first input step A first output step of applying each value and outputting a plurality of sample images to an output device based on the image data to which the plurality of adjustment candidate values are applied, respectively, and the original image and the first output step by an operator A second input step of inputting a result of subjective judgment of color tone by comparing the plurality of output sample images; and a result of the determination input in the second input step. For the image data input in the first input step, the calculation step for calculating the tone adjustment value based on the result of the determination converted into a numerical value in the numericalization step, And a second output step of applying the color adjustment value calculated in the calculation step and outputting an image to the output device based on the image data to which the color adjustment value is applied. And

  According to another invention, an image processing apparatus to which the method is applied is provided.

  Therefore, according to the present invention, when the color tone of an image is changed stepwise in order to obtain the optimum color tone adjustment value, even if the intermediate color tone of a plurality of outputs becomes a desired color tone, There is an effect that the color tone adjustment amount corresponding to the intermediate position can be obtained based on the determination result.

  Accordingly, it is not necessary to set the step of the color tone adjustment range in detail, and even if the step of the color tone adjustment range is large, it is not necessary to re-output to narrow down the color tone adjustment value. As a result, the number of output sample images for determination is reduced, so that the labor and time required for the operator's determination work can be reduced.

  Further, when the determination sample image is output to the printer, the number of output samples is reduced, and the consumption of paper and color materials (ink / toner) can be reduced.

  Furthermore, according to the present invention, since the determination of color tone comparison between the original image and the sample image may be a subjective determination, the adjustment value can be easily adjusted even by a person who does not necessarily have advanced knowledge or skill. There is an advantage that can be obtained.

  Furthermore, with simple subjective judgment, the subjective sense of comparison gradually paralyzes while gazing at the samples, and it is possible to correctly determine which of the approximated samples is closest to the original picture. It is also possible to reduce the sensory problem of disappearance.

1 is a block diagram illustrating a configuration of an image processing system to which a color tone adjustment method of the present invention is applied. 6 is a flowchart illustrating a color tone adjustment process according to the first embodiment. 6 is a diagram illustrating an example of a color tone adjustment color space (three-dimensional) according to Embodiment 1. FIG. 6 is a diagram illustrating an example of a color tone adjustment color space (two-dimensional) according to Embodiment 1. FIG. It is a figure which shows the mark sheet used for recording and input of the determination result according to Example 1. FIG. It is a figure explaining the color tone adjustment gravity center according to Example 1. FIG. 10 is a flowchart illustrating color tone adjustment processing according to the second embodiment. 6 is a diagram illustrating an example of a color tone adjustment color space (two-dimensional) according to Embodiment 2. FIG. It is a figure explaining the color tone adjustment gravity center according to Example 2. FIG.

  Hereinafter, preferred embodiments of the present invention will be described more specifically and in detail with reference to the accompanying drawings. The configurations disclosed in the following embodiments are merely examples, and the present invention is not limited to the illustrated configurations.

  FIG. 1 is a block diagram showing the configuration of an image processing system to which the color tone adjustment method of the present invention is applied. In FIG. 1, 101 is a personal computer (hereinafter PC), 102 is a keyboard, 103 is a display monitor, 104 is a high-definition color printer (hereinafter printer), 105 is a high-definition digital camera, and 106 is a flatbed scanner. . The digital camera 105 is connected to the PC 101, and image data captured by the digital camera 105 can be taken into the PC 101. Here, a printer and a display monitor (hereinafter referred to as a display) serve as an image output device in the color adjustment described below.

  Next, two embodiments using the system configured as shown in FIG. 1 will be described.

  In this embodiment, an example of application of the color adjustment method of the present invention will be described by taking as an example a case where a copy of an original image is created by a color printer using an artwork such as a picture as an original image.

  FIG. 2 is a flowchart showing the color tone adjustment processing according to the first embodiment of the present invention. A program operating on the personal computer 101 shown in FIG. 1 executes the processing shown in the flowchart of FIG.

  In step S10, image data obtained by photographing an original image (not shown) such as a picture with the digital camera 105 is input to the PC 101 (first input). The image data input to the PC 101 is color-converted to a color substantially similar to the original image by a known color matching technique, and the preparation of the output image data is completed. In such a color matching technique, an appropriate color profile (color conversion table) is prepared in advance in accordance with the illumination conditions at the time of photographing the original image and the color settings of the digital camera. Generally, image data that is adjusted to an appropriate color tone is generally generated by converting image data using this color profile.

  Note that there are various known techniques and commercially available tools as color profile creation methods for approximating the color of a subject photographed with a digital camera and the color of an output output by a printer. However, the color tone of the subject and the printer output actually does not reach a satisfactory level with the above color matching technology, and in fact, the operator often needs to finely adjust the color tone.

  In step S20, a plurality of color tone adjustment candidate values are set. The color tone adjustment candidate value is a combination of numerical values for changing the color tone of an image to be adjusted in a color space in which a certain color adjustment is performed. As a color space for color tone adjustment, RGB may be simply used, but CIE CAM97, CIE LAB, CIE LUV, etc. defined by the CIE (International Commission on Illumination) are more suitable for human perception characteristics. preferable. Therefore, in this embodiment, a case where CIE LAB is adopted will be described.

  In the case of CIE LAB, a color tone adjustment range and a color tone adjustment step are set for each of the three axes L *, a *, and b * representing each color component. For example, the following numerical values are set.

The adjustment range of L * is -4 to +4, the adjustment step of L * is 2,
The adjustment range of a * is -4 to +4, the adjustment step of a * is 2,
The adjustment range of b * is −4 to +4, and the adjustment step of b * is 2.

This assumes that an adjustment range is set as a cube as shown in FIG. 3 assuming an adjustment color space consisting of adjustment amounts (dL *, da *, db *) with respect to (L *, a *, b *). Become. In FIG. 3, the position of the grid point indicated by a black circle is a color tone adjustment candidate value. in this case,
(L * number of adjustment steps) × (a * number of adjustment steps) × (b * number of adjustment steps) = 5 × 5 × 5 = 125
As described above, 125 color tone adjustment candidate values are set. In many cases, if the adjustment is performed in the range of ± 4 on each of the L *, a *, and b * axes as in this example, it is sufficient for fine color adjustment.

Further, L * does not need to be changed when adjustment in the brightness direction is not required. In this case, (L * number of adjustment steps) × (a * number of adjustment steps) × (b * number of adjustment steps) = 1 × 5 × 5 = 25
As shown in FIG. 4, 25 color tone adjustment candidate values as shown in FIG.

  The color tone adjustment range as shown in FIG. 4 includes the accuracy and completeness of the color profile in step S10, the fluctuation characteristics of the printer and digital camera, the fluctuation characteristics of illumination, the spectral characteristics of the ink used in the printer and the color material of the work. May vary depending on various factors such as differences. Accordingly, the user may be able to directly input the color tone adjustment range and the color tone adjustment step via the keyboard 102 according to the situation. In this case, a program that performs input processing of information input via the keyboard 102 on the PC 101 is in charge of color tone adjustment candidate value setting processing.

  In step S30, the plurality of color tone adjustment candidate values set in step S20 are applied to the image data generated in step S10.

  That is, when the image data captured by the digital camera 105 is RGB data, the image data is converted from RGB to image data expressed in the CIE LAB space by a known calculation. Next, one of the tone adjustment candidate values set in step S20 is added to the image data in the CIE LAB color space. For example, if one of the tone adjustment candidate values (dL *, da *, db *) is (−4, −4, −4), the L *, a *, b * component values of all the pixels of the image data. Subtract 4 from Next, the image data expressed in the CIE LAB space is converted into image data expressed in the RGB space by a known calculation to generate one tone adjustment candidate image data. Such a process is performed for all color adjustment candidate values, and a plurality of color adjustment candidate image data is generated. When there are 75 color tone adjustment candidate values, 75 sets of image data are generated. Of course, when the color tone adjustment value is (0, 0, 0), it is not necessary to convert the image data.

  In step S40, all of the plurality of tone adjustment candidate image data generated in step S30 are output by the printer 104 (first output). When there are 75 color tone adjustment candidate values, 75 sample images are output. The operator visually compares all output samples (output images) and the original image to determine the degree of approximation. At this time, it is not necessary to strictly determine the degree of approximation, and simple subjective determination may be used. For example, there are two stages “different” / “close” or three stages “different” / “close” / “pretty close”. For example, a mark sheet as shown in FIG. 5 is prepared in advance, and the determination result for each image is recorded by painting the mark.

  In step S50, the operator's determination result is input to the PC 101 (second input). In this embodiment, for example, the determination result recorded on the mark sheet as shown in FIG. 5 is read as image data by the flat bed scanner 106. This image data is input to the PC 101, and the mark sheet image is analyzed by a determination result input program operating on the PC 101.

  When the system configuration does not include a flat bed scanner, the operator may input the result of visual comparison from the keyboard 102 to the PC 101 each time. In this case, a program that processes keyboard input that operates on the PC 101 is in charge of processing of determination result input.

  There are the following methods for more accurately determining the color tone. In other words, the order of output samples for color tone determination is random, pseudo-random, or an image that precedes and follows the determination sequence in order of little correlation of color tone adjustment values. Against this background, there is a problem that if the tone judgment is repeated in an order that changes the tone gradually instead of random, a sensory hysteresis occurs for the judgment, and the judgment result slightly shifts to the whole. Is generated. Therefore, if the output order of the sample images to be judged is random, pseudo-random, or the order of the order in which the correlation of the color tone adjustment values is low in the order of the judgment order, such sensory hysteresis is prevented. can do.

  In this case, in order to reduce work load and mistakes, it is desirable that the order change be performed inside the PC 101. In other words, in the PC 101, the order in which the color tone adjustment candidate images are printed from the printer is random, pseudo-random, or the images before and after in the determination order are rearranged in the order of little correlation of the color tone adjustment values and output. Then, the operator makes a determination in the order in which they are output, and records the result in the determined order in the mark sheet. Next, the PC 101 rearranges the plurality of determination results obtained by reading the results from the mark sheet so that the rearrangement at the time of printer output is restored. By doing in this way, the problem of a sensory hysteresis can be reduced, preventing a worker's burden and mistake.

  In step S60, a weight value used for later calculation is set for each stage of the determination result. For example, if the number of determination levels is “different” / “close”, the weight values may be 0 and 1, respectively. Further, if the number of determination stages is three stages such as “different” / “close” / “pretty close”, the weight value is set to a value such as 0 for different, 1 for close, and 3 for fairly close.

  Here, the setting ratio of the weight value for each determination stage other than “different” is examined. This ratio is preferably a value that is roughly proportional to a sensory impression such as “close” or “substantially close” that expresses the degree of judgment. However, since it is generally difficult to quantify the sensation, it is realistic to obtain an optimal value based on some demonstration experiment.

  According to the inventor's study, if a value of 1: 2 or about 1: 3 is set as a weighting ratio for the determination based on the terms “close” and “substantially close”, the determination is generally good. The result is obtained. As this weight value, a value registered in advance as a program operating on the PC 101 may be used, or an operator may be able to adjust the weight value via the keyboard 102. In this case, the program that processes the keyboard input of the weight value is in charge of the weight setting process.

  In step S70, a color tone adjustment value is calculated. The color tone adjustment value is calculated using the formulas (1), (2), and (3) based on the determination result input in step S50 and the weight value set in step S60.

  Here, N is the total number of color tone adjustment candidates (number of output samples), j (i) is a numerical value representing the determination result for the i th color tone adjustment output sample. Assign 2 to “close” and 3 to “close”. w (n) is a weight value for each determination result, and w (1) = 0, w (2) = 1, and w (3) = 3 are assigned to reflect the previous setting example. DL * (i) is the adjustment amount of L * when the i th color adjustment output sample is generated, da * (i) is the adjustment amount of a * when the i th color adjustment output sample is generated, and db * (i ) Is the adjustment amount of b * when the i th color tone adjustment output sample is generated.

  The color tone adjustment values obtained by Equation 1, Equation 2, and Equation 3 correspond to the center of gravity when the weight values corresponding to each determination result are distributed to each adjustment coordinate in the color tone adjustment color space. FIG. 6 is a diagram for explaining the calculation of the adjustment amount on the two-dimensional plane of a * and b *. In FIG. 6, examples of determination results are plotted as white circles, black circles (small), and black circles (large) on the coordinates corresponding to the respective color tone adjustment candidate values. Here, white circles, black circles (small), and black circles (large) represent “different”, “close”, and “pretty close”, respectively.

As a result of these determinations, 0, 1, and 3 are assigned as weight values to “different”, “close”, and “substantially close”, respectively. Then, by applying the calculations of Equations 1 and 2, the coordinates (da * _Adj , db * _Adj ) of the point A, which is a substantially circular centroid position expressed as “near” and “very close”, are (1. 2, 0.9). When adjustment is performed in a two-dimensional space such as the a * and b * directions, at least three determination results other than “different” are required. When the color tone adjustment space is two-dimensional and there are two or less determination results other than “different”, it is desirable that an appropriate determination result may not be obtained, so that it is processed as an error.

FIG. 6 illustrates a case where color tone adjustment is performed on a two-dimensional plane of da * -db *. This is expanded in the L * axis direction. In this case, the coordinates (dL * _Adj , da * _Adj , db * _Adj ) of the center of gravity of the substantially spherical body expressed as “near” and “substantially close” are calculated by _equations 1, 2, and 3. The coordinates of the gravity center position calculated in this way become the final color tone adjustment value.

  In this embodiment, an example in which the position of the center of gravity is strictly determined has been described. For example, when the determination is expressed in two stages such as “different” / “close”, the center coordinates of the distribution range of determination “close” May be obtained as the adjustment position. In this case, the accuracy may be lower than when the center-of-gravity position is obtained, but there is an advantage that the calculation can be simplified. Further, if it is possible to obtain the center of gravity and the center position in general, the calculation does not need to strictly follow the equations 1, 2, and 3.

In step S80, the color tone adjustment value obtained in step S70 is applied to the image data generated in step S10. When the image data captured by the digital camera 105 is RGB image data, the RGB image data is converted into LAB image data expressed in the CIE LAB space by a known calculation. Then, the color tone adjustment values (dL * _Adj , da * _Adj , db * _Adj ) obtained in step S70 are added to the LAB image data. Thereafter, the LAB image data is converted again into RGB image data by a known calculation, and color tone adjusted image data is generated.

  Finally, in step S90, the color tone adjusted image data generated in step S80 is output to the printer 104 (second output). In this way, an output result (output image) whose color tone has been adjusted is obtained, which becomes a duplicate of the original image.

  According to the embodiment described above, even when the intermediate color tone of a plurality of outputs becomes a desired color tone, the color tone adjustment amount corresponding to the intermediate position can be obtained based on the peripheral determination result. Accordingly, it is not necessary to set the step of the color tone adjustment range in detail, and even if the step of the color tone adjustment range is large, there is no need for re-output to narrow down the color tone adjustment value. Thereby, the number of outputs for determination can be reduced, and the labor and time of determination work of an operator can be reduced. In addition, the number of output samples for determination is reduced, and the consumption of paper and color materials (ink and toner) can be reduced.

  Furthermore, according to this embodiment, since the judgment of visual comparison of the colors may be a simple subjective judgment, even a person who does not necessarily have advanced knowledge or skill can easily work. Can do. That is, anyone can obtain the adjustment value. Furthermore, by changing the judgment order of multiple images, the subjective sense of comparison gradually paralyzes during sample comparison, making it impossible to correctly determine which of the approximated samples is closest to the original image. It is also possible to reduce the above problem.

  In the second embodiment, an example in which the color adjustment method of the present invention is applied will be described, taking as an example a case where a copy of an original image is accurately output on a display monitor using a work such as a picture as an original image. In this embodiment, since the color tone adjustment is performed based on the display on the display monitor 103, it is desirable that the display monitor 103 is appropriately calibrated using a commercially available calibration tool. Further, an original image is arranged beside the display monitor 103 so that the monitor display and the original image can be compared side by side.

  FIG. 7 is a flowchart showing a color tone adjustment process according to the second embodiment of the present invention. A program operating on the personal computer 101 shown in FIG. 1 executes the processing shown in the flowchart of FIG.

  In step S <b> 101, image data obtained by photographing an original image (not shown) such as a picture with the digital camera 105 is input to the PC 101. Since this point is the same as that of the first embodiment, a duplicate description is omitted. Note that there are various known techniques and commercially available tools as a color profile creation method for approximating image data obtained by photographing with a digital camera to an image displayed on a display monitor. However, the color of the subject and the output of the display monitor actually does not reach a satisfactory level with the above color matching technique, and actually the operator often needs to finely adjust the color.

  In step S102, a plurality of tone adjustment candidate values are set. The color tone adjustment candidate value is a combination of numerical values for changing the color tone of the target image in a color space in which a certain color adjustment is performed. Here, the RGB color space used in many digital cameras and display monitors is used as a color space for color tone adjustment.

  In the case of RGB, a color tone adjustment range and a color tone adjustment step are set for each of the three axes R, G, and B representing each color component. For example, an adjustment value in a range that satisfies the following conditions is set.

r = 16,
The R adjustment range is -r to + r, the R adjustment step is 4,
The adjustment range of G is -r to + r, the adjustment step of G is 4,
The adjustment range of B is -r to + r, the adjustment step of B is 4,
Condition: √ (dR * dR + dG * dG + dB * dB) ≦ r.

  When an adjustment color space consisting of adjustment amounts (dR, dG, dB) with respect to (R, G, B) is assumed, this is configured every 4 steps within a range of ± 16 on each axis of dR, dG, dB. Among the lattice points, the lattice point whose distance from the origin is within 16 is defined as the adjustment amount. For easy understanding, FIG. 8 shows a dR-dG plane when dB = 0. In FIG. 8, the positions of the grid points indicated by black circles are the color tone adjustment candidate values. On the dR-dG plane when dB = 0, there are 49 color tone adjustment candidate values. When this is expanded to a three-dimensional space of (dR, dG, dB), there are 257 tone adjustment candidate values.

  Such a color tone adjustment range and a color tone adjustment step may be directly input by the user via the keyboard 102. In this case, a program that processes keyboard input that operates on the PC 101 is in charge of the process of setting the tone adjustment candidate value.

  In step S103, a plurality of tone adjustment candidate values are rearranged in a random order, pseudo-random, or an image before and after in the order of determination in the PC 101 in an order with little correlation of the tone adjustment values. In step S104, the tone adjustment candidate values are applied to the image data generated in step S101 in the order rearranged in step S103. For example, if the color tone adjustment candidate value (dR, dG, dB) is (-4, 0, -8), -4 is added to R of all the pixels of the image data, 0 is added to G, and -8 is added to B. To do. Of course, when the color tone adjustment value is (0, 0, 0), it is not necessary to convert the image data.

  In step S <b> 105, the image data that has been subjected to the color tone adjustment in step S <b> 104 is displayed on the monitor 103. Then, the operator compares the color tone of the original image and the image displayed on the monitor 103 to make a determination. At this time, it is not necessary to strictly determine the degree of approximation, and simple subjective determination may be used. For example, there are two stages “different” / “close”, or three stages “different” / “slightly close” / “close”.

  In step S <b> 106, the worker inputs the result of the visual comparison to the PC 101 via the keyboard 102 each time. In this case, a program that processes keyboard input that operates on the PC 101 is in charge of processing of determination result input. In step S107, it is checked whether or not the determination for all color tone adjustment candidate values has been completed. If it is determined that there is a color adjustment value for which determination has not been completed, the process returns to step S104 to perform determination for the next color adjustment candidate value. On the other hand, if it is determined that all the color tone adjustment values have been determined, the process proceeds to step S108.

  In step S108, a weight value used for later calculation is set for each stage of the determination result. For example, if the determination is two-step determination such as “different” / “close”, the weight values may be 0 and 1, respectively. Further, if the determination is three-step determination such as “different” / “slightly close” / “close”, for example, different weight values are set to 0, slightly close to 1, and close to 2.

  Here, the setting ratio of the weight value for each determination stage other than “different” is examined.

  As in the first embodiment, this ratio is desirably a value that is generally proportional to a sensory impression such as “slightly close” or “close” that expresses the degree of determination. However, since it is generally difficult to quantify the sensation, it is realistic to obtain an optimal value based on some demonstration experiment. According to the inventor's study, if a value of 1: 2 or about 1: 3 is set as the weighting ratio for the determination based on the terms “slightly close” and “close”, the determination is generally good. The result is obtained.

  As this weight value, a value registered in advance as a program operating on the PC 101 may be used, or an operator may be able to adjust the weight value via the keyboard 102. In this case, a program for processing keyboard input that operates on the PC 101 is responsible for weight setting processing.

  In step S109, a color tone adjustment value is calculated. The color tone adjustment values (dRadj, dGadj, dBadj) are calculated using Equation 4, Equation 5, and Equation 6 based on the determination result input in Step S106 and the weight value set in Step S108.

  Here, N is the total number of color tone adjustment candidates (number of output samples), j (i) is a numerical value representing the determination result for the i th color tone adjustment output sample. 2 is assigned to “slightly close” and 3 is assigned to “close”. w (n) is a weight value for each determination result, and w (1) = 0, w (2) = 1, and w (3) = 2 are assigned to reflect the previous setting example. dR (i) is the R adjustment amount when generating the i th color adjustment output sample, dG (i) is the G adjustment amount when generating the i th color adjustment output sample, and dB (i) is the i th color adjustment. This is the adjustment amount of B when generating the output sample.

  The color tone adjustment values obtained by Equations 4, 5, and 6 correspond to the center of gravity when the weight values corresponding to the respective determination results are distributed to the respective adjustment coordinates in the color tone adjustment color space. FIG. 9 is a diagram for explaining the calculation of the adjustment amount by taking a two-dimensional plane of R and G as an example for ease of explanation. In FIG. 9, examples of determination results are plotted as white circles, black circles (small), and black circles (large) on the coordinates corresponding to the respective color tone adjustment candidate values.

  White circles, black circles (small), and black circles (large) represent “different”, “slightly close”, and “close”, respectively, and as a result of judgment, “different”, “slightly close”, and “close” 0, 1, 2 are assigned as weight values. Then, when Expressions 4 and 5 are applied, the coordinates (dRadj, dBAdj) of the point A that is a substantially circular barycentric position expressed by “slightly close” and “close” are (−1.2, −6. 3) Calculated as follows.

  FIG. 9 illustrates a two-dimensional plane of dR-dB as an example. When this is expanded in the dG axis direction, the coordinates of the center of gravity of the substantially spherical body expressed as “slightly close” or “close” (dRadj, dGadj, dBAdj) is calculated by Equations 4, 5, and 6. The coordinates of the gravity center position calculated in this way become the color tone adjustment value. If the center of gravity and the center position can be obtained roughly, the calculation does not have to strictly follow the equations (4), (5), and (6).

  In step S110, the color tone adjustment value obtained in step S109 is applied to the image data generated in step S101. That is, the color tone adjustment image data is generated by adding the color tone adjustment values (dRadj, dGadj, dBadj) obtained in step S109 to the RGB values of the image data captured by the digital camera 105.

  In step S111, the color tone adjusted image data generated in step S110 is output to the display monitor 103. In step S112, the color tone of the original image and the image displayed on the display monitor 103 are compared. Here, if the color tone of the displayed image is OK, the operation ends.

  On the other hand, if the color tone adjustment is insufficient, when this is input to the PC 101, the process returns to step S102, and the color tone around the color tone adjustment values (dRadj, dGadj, dBadj) obtained earlier is the center. Set the range of adjustment candidates. Since sufficient narrowing down to the optimum color tone has already been performed, the color tone setting range may be sufficiently narrowed and the color tone adjustment step may be set finely. Thereafter, steps S103 to S111 are re-executed based on the plurality of reset color tone adjustment candidate values. Even when it is necessary to readjust the color adjustment value in this way, the adjustment value close to the desired color adjustment value is obtained in a single process, so the color adjustment range necessary for narrowing down is greatly reduced. be able to. Through the above processing, the color tone of the display monitor display can be precisely matched to the original image.

  As described above, according to this embodiment, even when the intermediate color tone of a plurality of outputs becomes a desired color tone, the color tone adjustment amount corresponding to the intermediate position can be obtained based on the determination result in the vicinity. Is possible. Therefore, it is not necessary to set the step of the color tone adjustment range in detail, and the step of the color tone adjustment range may be large. Further, even when it is necessary to further narrow down the color tone adjustment value, it is possible to narrow the color tone adjustment range and reduce the determination load.

  Further, according to this embodiment, the determination of the visual comparison of the tint between the original image and the color tone adjustment output is a simple subjective determination, for example, a two-step determination of “different” / “close”, or “ A three-step determination such as “different” / “slightly close” / “close” is sufficient. With such a determination, even a person who does not necessarily have advanced knowledge or skill can easily work, and anyone can obtain an adjustment value.

  Furthermore, by changing the judgment order of multiple images, the subjective sense of comparison gradually becomes paralyzed during the comparison of the samples, and it is correctly determined which of the approximated samples is closest to the original picture. It is possible to reduce the sensory problem of being unable to do so.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and the computer (or CPU, MPU, etc.) of the system or apparatus executes the program. It is a process to read and execute.

Claims (6)

A color adjustment method for adjusting the color tone of an output image image-processed by an image processing apparatus,
A first input step in which the image processing apparatus inputs image data of an original image of the output image to be adjusted in color tone;
A setting step for setting a plurality of adjustment candidate values for adjusting the color tone of the output image;
A plurality of adjustment candidate values set in the setting step are respectively applied to the image data input in the first input step, and a plurality of adjustment values are applied based on the image data to which the plurality of adjustment candidate values are respectively applied. A first output step of outputting a sample image to an output device;
A second input step for inputting a result of subjective judgment of color tone by comparing the original image by the operator and the plurality of sample images output in the first output step;
A quantification step for quantifying the determination result input in the second input step;
A calculation step of calculating a color tone adjustment value based on the result of the determination digitized in the digitization step;
Applying the color tone adjustment value calculated in the calculation step to the image data input in the first input step, and outputting an image to the output device based on the image data to which the color tone adjustment value is applied And a second output process. An image processing apparatus that adjusts the color tone of an image and outputs the image,
First input means for inputting image data of an original image of an output image from the image processing apparatus to be subjected to color tone adjustment;
Setting means for setting a plurality of adjustment candidate values for adjusting the color tone of the output image;
A plurality of adjustment candidate values set by the setting unit are respectively applied to the image data input by the first input unit, and a plurality of adjustment values are applied based on the image data to which the plurality of adjustment candidate values are respectively applied. First output means for outputting a sample image to an output device;
Second input means for inputting a result of subjective judgment of color tone by comparison of the original image by the operator and the plurality of sample images output by the first output means;
Quantification means for quantifying the determination result input by the second input means;
A calculation unit that calculates a color tone adjustment value based on the determination result digitized by the digitization unit;
Applying the color tone adjustment value calculated by the calculation unit to the image data input by the first input unit, and outputting an image to the output device based on the image data to which the color tone adjustment value is applied And a second output means.   Changing means for changing the output order of the plurality of sample images to the output device at random or in an order in which the correlation of the color tone adjustment values of the sample images before and after the judgment order by comparison by the operator is small. The image processing apparatus according to claim 2, further comprising:   The image processing apparatus according to claim 2, wherein the output device is a printer or a display.   The calculating means distributes the digitized determination results corresponding to each of the plurality of sample images on a color space for color tone adjustment, and calculates coordinates corresponding to the center of gravity or the center of the distributed determination results. 6. The image processing apparatus according to claim 2, wherein the coordinate value is a color tone adjustment value.   A program that causes a computer to function as each unit of the image processing apparatus according to claim 2.

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