CN103002193A - Digital image adjustment system and method - Google Patents

Abstract

The invention relates to an image adjusting system. The image adjusting system comprises a color management unit and a second color adjusting unit, the color management unit is used for primary color adjustment for first digital images and capable of obtaining characteristic color patch files after primary color adjustment, and the second color adjusting unit comprises a key color testing label, a color comparison module, a color transformation module and an image generation module, wherein color values in the key color testing label are color values capable of correctly outputting typical colors in appointed output equipment after human eye judgment; the color comparison module is used for comparing the characteristic color patch files subjected to primary color adjustment with the color values of color blocks in the key color testing label one by one and computing color difference among the characteristic color patch files and the color values; the color transformation module is used for secondary color adjustment for the corresponding color values of the characteristic color patch files subjected to primary color adjustment when the color difference is within the specified threshold value range so that the characteristic color patch files subjected to secondary color adjustment are obtained, and secondary color adjustment refers to the color values of the corresponding color blocks in the key color testing label; and the image generation module is used for generating second digital images according to the characteristic color patch files subjected to secondary color adjustment.

Description

Digital image adjustment system and method

1. Technical field

The present invention belongs to the field of image printing, and can be further used for image display and/or output of other media, such as displays, color inkjet, thermal sublimation printing, digital printing, etc. The final result of the present invention is to make images appear in different media Output devices can be as similar as possible. the

2. Background technology

Due to the development of computer and network technology, there are many devices for acquiring, transmitting, reproducing and outputting digital images, and these devices belong to different manufacturers and use different technologies. When reproducing the same digital image, the reproduction visual effects of different devices The difference is very large, which has caused great troubles to users, and cannot realize what you see is what you get. the

In order to achieve what you see is what you get between different devices, the following two color adjustment methods are mainly used in the prior art: one is based on the characteristics of the image color itself, such as the reading and correction methods of parameters such as grayscale histograms , this kind of method ensures the reasonable distribution of each channel of the image in the tone level, but it cannot process the color reproduction ability according to different devices, so after being transmitted to different devices, the color of the image will still change due to the limitations of the device , resulting in color distortion, and the color deviation is unpredictable; the second method is color management, and the color is safely converted on different devices through a device-independent color space. Although this method takes into account different devices and different color spaces to reproduce colors ability, but the whole process mainly depends on the pros and cons of color management software, and there are not many factors that can be controlled by humans. That is to say, when using the same color management software to convert images, there is almost no difference in the generated ICC. Even if the image color is not ideal after using ICC, there is no effective way to correct it reasonably. But regardless of any image, the color effect is ultimately based on the judgment of the customer or the viewer, and color management is only a repeated modification of the color without changes, which cannot effectively guarantee this process. the

Based on previous theoretical research, it can be known that human beings have a great deal of memory color (memory color refers to the color stored in the long-term memory acquired by the human visual system, that is to say, the colors of objects experienced and recognized by people can be found in memory), such as skin color The observation of hair, fruit, plants, animals, etc. is very sensitive, and the color difference of the memory color in the image is often easier to be discovered by people, which makes people feel different color stimuli. Therefore, for the observer, the color reproduction status of the memory color plays a very important role in the consistency of the image. the

For example, US2004/0156244A1 discloses a method of adjusting image output by using memory color, which firstly calibrates the digital image, then performs region extraction on the calibrated image, and uses memory color to calibrate the background image after region extraction , to get the calibrated digital image. This adjustment method ensures accurate reproduction of the memory color in different output devices. However, the disadvantage of this calibration method is that although it can guarantee the accuracy of the memory color area, it cannot guarantee that the overall visual effect of the entire picture will still maintain a high visual consistency when switching between different devices. the

WO2007/052485A1 and JP2006-246376A also disclose similar technical solutions for calibrating using memory colors, and their disadvantages are similar to those of US US2004/0156244A1. the

EP1089552A2 discloses a method of how to use memory color for digital image calibration, which describes in detail the process of memory color for digital image calibration. But it has similar disadvantages as the above documents. the

It can be seen from this that how to maintain a relatively consistent visual effect between devices with different color gamut spaces and color gamut reproduction effects, taking into account the color reproduction capabilities of different devices; It is a problem to be solved to be consistent with the original color of things and to take care of the observer's aesthetic standards. the

3. Contents of the invention

The present invention is a digital image adjustment system or method invented to solve the above-mentioned problems in the prior art. The system or method can improve the human visual consistency of image color when color reproduction can be performed between different devices. the

Specifically, the present invention solves the above problems by adopting the following technical means:

The present invention provides an image adjustment system, which includes: a color management unit, which performs the first color adjustment on the first digital image, and can obtain the characteristic color standard file after the first color adjustment; the second color An adjustment unit, the second color adjustment unit includes: a key color test plate, the color value in the key color test plate is a value that can correctly output a typical color after being judged by the human eye in the designated output device, a color comparison module, The color comparison module compares the characteristic color standard file after the first color adjustment with the color block color value in the key color test standard plate one by one, calculates the color difference between them, and the color transformation module, when said When the color difference is within the specified threshold, the second color adjustment is performed on the corresponding color value in the characteristic color standard file after the first color adjustment, and the second color adjusted characteristic color standard file is obtained. The secondary color adjustment refers to the color value of the corresponding color block in the key color test plate, and the image generation module generates the second digital image according to the characteristic color standard file after the second color adjustment. the

The invention further provides a method of using such a system. the

The present invention also provides an image adjustment method, which includes: a color management step, the color management step performs the first color adjustment on the first digital image, and can obtain the characteristic color standard file after the first adjustment; The second color adjustment step, the second color adjustment step includes: providing a key color test plate, the color value in the key color test plate is a value that can correctly output a typical color after being judged by human eyes in the specified output device, The color comparison step, the color comparison module compares the characteristic color standard file after the first color adjustment with the color block color values in the key color test standard plate one by one, and calculates the color difference between them, the color transformation step , when the color difference is within the specified threshold, the second color adjustment is performed on the corresponding color value in the first adjusted characteristic color scale file to obtain the second adjusted characteristic color scale file, the The second color adjustment refers to the color value of the corresponding color block in the key color test plate, and the image generation step generates a second digital image according to the characteristic color standard file after the second color adjustment. the

Further, the characteristic color scale file after the first adjustment is an ICC file. the

Further, in the system or method, the key color includes a memory color and/or a color representing a boundary of the color gamut of the specified device and/or a specified position in the color gamut of the specified device. Further, in the system or method, the numerical value of the color difference is Lab numerical value, XYZ numerical value, RGB numerical value or CMYK numerical value. the

Further, in the system or method, the typical color is changed according to different observation objects. Further, in the system or method, the typical color is changed according to the content of the first digital image. Further, in the system or method, an adjustment curve is output after the ICC file is compared with the color in the key color test plate, and the adjustment curve is used to adjust the digital image. The conversion is performed according to the output adjustment curve. Further, in the system or method, the adjustment curve is adjustable. It should be pointed out that by adopting the above-mentioned personalized adjustment method, the output image can better meet the visual judgment of human eyes, and has further prominent substantive features and significant progress. the

By adopting the above-mentioned technical means, the present invention overcomes the technical problem of incompatibility between the two on the basis of the existing color management, and adds the correction of the key color of the image based on the memory of the human eye, so as to ensure that both The color gamut between different devices also takes into account the aesthetic feelings of the observer, which not only ensures the color space conversion of the color that has nothing to do with the device, but also conforms to the subjective aesthetic standards of people, and realizes both subjective and objective considerations. the

4. Description of drawings

Figure 1 is the workflow diagram of color management in traditional prepress adjustment

Fig. 2 is a schematic diagram of the working mode for adjusting images in the present invention

Fig. 3 is a working principle diagram of the system or method in the present invention

5. Specific implementation

The specific implementation of the present invention will be further explained below in conjunction with the accompanying drawings. Of course, this description is only exemplary. Those skilled in the art can use other technical means and methods to modify, perfect or deform the technical details in the present invention. Obviously Such changes will not depart from the inventive essence of the present invention. the

Fig. 1 is a schematic diagram of general digital image color adjustment, wherein the first image is an original image, in order to obtain a better display effect on the output device, it is necessary to adjust the color values of multiple pixels in the first image through an adjustment module, Therefore, it is possible to obtain a digital second image, and the digital second image is suitable for a specific device, such as a printer, a printing machine, a display, a projector, and the like, and has a better display effect. the

The above are the traditional image adjustment methods, the advantages and disadvantages of which have been clarified in the background art, and will not be repeated here. the

Fig. 2 is a working principle diagram of the system and method of the present invention, wherein, after the original image is calibrated by the color management system, a key color adjustment module based on human vision is used for key color adjustment, and the key color adjustment module first calls the color After managing the ICC, look up the memory color in it, retrieve the memory color database of the system, and after determining the difference between the memory color in the image and the standard value, modify it to generate a new adjusted second image, after adjustment The resulting second image will be used for output on a specific device. the

The specific working method of the key color adjustment module in the present invention is as follows:

First, select different key color test plates according to different equipment, the key color test plate is preferably a digital file, which records a large number of key color values, these key colors are the colors with the best display effect in specific equipment The value, the content of the test standard plate set by different devices is different. For example, in a printing machine, when the Lab value of the sky color is set to (x, y, z), the printed matter has the best visual effect, while in another printing machine, the Lab value of the sky color is set to The effect is the best when it is set to (x', y', z'), so different devices require different values of the test plate, but these values point to the same content, that is, the color of the sky, which is the A key color. the

Then, compare the L'a'b' value of each color block in the ICC file after the color change by the color management software with the value in the test plate, when a certain color block A in the ICC file When the color difference ΔE between the color value of the color value and the Lab value of a certain color block B in the test plate is within a certain range, it is considered that the above-mentioned color block A in the ICC file and the color block B in the key color test plate are to represent Key colors are consistent. The determination of ΔE can be deduced based on known techniques, including but not limited to the use of statistics, analysis of human visual latitude and other related methods . At this time, modify the key color value of color block A in the ICC file to the value of color block B in the key color test plate, that is, complete the comparison and adjustment. After the adjustment, the corresponding colors in the color-managed digital image in the entire digital image 1 are modified to obtain the adjusted digital image 7 . More preferably, the adjustment curve can be output after comparing the colors in the ICC file and the key color test plate, and the adjustment curve is used to adjust the digital image. Further, the adjustment curve is also adjustable. Such adjustment Some special key colors will be further highlighted in the output effect, with more unexpected effects. The resulting digital image is intended for output on a specific device.

The key color in the key color test target plate 7 wherein is preferably the test target plate comprising the memory color, and its color value is the best color value for the memory color expressive force in this specific device judged by a standard observer, Such as grass, sky, strawberry color, etc. After these colors are selected, find out the correct reproduced color through evaluation by a large number of standard observers, use related equipment to measure its Lab value, and obtain the standard color value. the

More preferably, the key color includes a memory color and a characteristic color , for example, a color representing a border or a special position within the color gamut of the specified device, and these colors may not correctly display standard colors on other devices. Of course, the key color test standard plate can also be or include other specific color values based on human eye observation and judgment. Furthermore, it can be personalized and selected according to different printing images. These settings can be adjusted according to the actual situation. In this way, personalized effects that change according to different observation groups can be obtained, with unexpected characteristics.

Since the color value in the key color test plate is the color data judged by the human eye, the digital image adjusted by using it will take care of the human eye after output, so that it has a more excellent visual effect. In this way, it is ensured that the color gamut between different devices and the feelings of the observers are taken into account during the color conversion, which not only ensures the color space conversion that has nothing to do with the device, but also can be carried out according to human subjective aesthetic standards. The adjustment realizes the comprehensive utilization of subjective and objective. the

Claims (10)

1. An image adjustment system comprising: A color management unit, the color management unit performs the first color adjustment on the first digital image, and can obtain the characteristic color standard file after the first color adjustment; The second color adjustment unit, the second color adjustment unit includes: The key color test plate, the color value in the key color test plate is the value that can correctly output the typical color after being judged by human eyes in the specified output device, A color comparison module, the color comparison module compares the characteristic color standard file after the first color adjustment with the color block color values in the key color test standard plate one by one, and calculates the color difference between them, The color conversion module, when the color difference is within the specified threshold, performs a second color adjustment on the corresponding color value in the feature color scale file after the first color adjustment, and obtains the second color adjustment feature color standard file, the second color adjustment refers to the color value of the corresponding color block in the said key color test standard plate, The image generation module generates a second digital image according to the characteristic color scale file after the second color adjustment. 2. The image adjustment system according to claim 1, wherein the characteristic color scale file after the first adjustment is an ICC file. 3. The image adjustment system according to claim 1-2, wherein the key color comprises a memory color and/or a color representing a color gamut border of the specified device and/or a specified position in the color gamut of the specified device. 4. The image adjustment system according to claims 1-3, wherein the value of the color difference is Lab value, XYZ value, RGB value or CMYK value. 5. The image adjustment system according to claims 1-4, wherein the typical color is changed according to different observation objects. 6. The image adjustment system according to claims 1-5, wherein the typical color is changed according to the content of the first digital image. 7. image adjustment system as claimed in claim 2, is characterized in that, output adjustment curve after comparing the color in this ICC file and key color test standard plate, adopt this adjustment curve to adjust digital image described conversion is according to the output adjustment curve. 8. The image adjustment system according to claim 7, wherein the adjustment curve is adjustable. 9. An image adjustment method, comprising: A color management step, the color management step performs the first color adjustment on the first digital image, and can obtain the characteristic color standard file after the first adjustment; The second color adjustment step, the second color adjustment step includes: Provide a key color test plate, the color value in the key color test plate is the value that can correctly output the typical color after being judged by human eyes in the specified output device, The color comparison step, the color comparison module compares the characteristic color standard file after the first color adjustment with the color block color values in the key color test standard plate one by one, and calculates the color difference between them, The color conversion step, when the color difference is within the specified threshold, the second color adjustment is performed on the corresponding color value in the first adjusted characteristic color scale file to obtain the second adjusted characteristic color scale file, the second color adjustment refers to the color value of the corresponding color block in the key color test plate, The image generation step is to generate a second digital image according to the characteristic color scale file after the second color adjustment. 10. An image adjustment method, characterized in that the image adjustment system according to any one of claims 1-8 is used to adjust the image.

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