CN112073594B - Ash balance adjusting method and device and computer readable storage medium - Google Patents
Ash balance adjusting method and device and computer readable storage medium Download PDFInfo
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Abstract
The invention discloses a method and a device for adjusting ash balance and a computer readable storage medium, which relate to the technical field of ink-jet printing, wherein the method comprises the following steps: acquiring a cyan, magenta and yellow mixed image according to the initial correction curve; judging whether the three-color mixed graph is in a gray balance state or not; if the three-color mixed image is not in a gray balance state, respectively adjusting the overall percentage of the three-color channels, and performing re-fitting and smoothing processing on initial reference curve data according to the adjustment amplitude values of the overall percentages of the cyan, magenta and yellow channels to obtain new reference curve data; generating a second correction curve according to the new reference curve data; repeating the steps until the three-color mixed graph is in a gray balance state. Through testing different inks, the invention has stronger robustness, and the overall color cast of the cyan, magenta and yellow mixed images is consistent without rainbow phenomenon.
Description
Technical Field
The invention relates to the technical field of color ink-jet printing, in particular to a method and a device for adjusting gray balance and a computer readable storage medium.
Background
With the development of color jet printing technology, the role of color management in jet printing production is more and more important, and the key technology of color is how to correctly reproduce gray in an original is the core of jet printing quality control. Therefore, the control of the gray balance has significance for faithfully reproducing the original and obtaining high-quality printed matters, and is an important link for realizing the datamation, normalization and standardization of printing production.
The Gray Balance (Gray Balance) means that three color plates of yellow (39Y), magenta (39M) and cyan (50C) present neutral Gray on a printed matter according to different dot area ratio. In the RGB color mode, R: g: b =1:1:1, the red, green and blue values are equal, namely neutral gray. Theoretically, equal amounts of C, M, and Y inks can be mixed to produce a neutral gray color. However, in reality, the color effect of the ink is limited by industrial production conditions, and the color developing abilities of C, M and Y are different, wherein the color developing ability of M is strongest, and the color developing ability of C is weakest, so that the same amount of C, M and Y ink can not generate neutral gray, but can generate reddish gray. To obtain a neutral gray color, the specific gravity of the C ink must be increased, which is the basic principle of print gray balance. It is the basis for any color separation method to realize correct color reproduction, and if the gray balance cannot be realized during color separation, the gray color in the original document is no longer gray after copying, and other colors inevitably produce color cast.
The method for controlling the ash balance mainly comprises the steps of manually adjusting the ash balance, an ash balance curve, an ash step scale, an ash balance test chart (colorimeter), a G7 process and the like. The main method of the G7 process is to measure and control the Neutral gray balance on the printed sheet by a spectrophotometer and match the visual effect of the image with a new NPDC Curve (Neutral Print sensitivity Curve). These methods have the following drawbacks:
1. the traditional printing process takes solid density and dot gain as main control objects, gray balance is not involved, and the existing G7 process is complex and has long implementation time.
2. In the process of adjusting the gray balance, a rainbow phenomenon is easy to appear, namely, the phenomenon of color cast appears in a plurality of places of the three-color gradual change strip.
3. The manual adjustment of the ash balance curve has large workload and low efficiency.
Disclosure of Invention
The invention mainly aims to provide an ash balance adjusting method, an ash balance adjusting device and a computer readable storage medium, and aims to solve the technical problems that the existing ash balance adjusting operation is complex and a rainbow phenomenon is easy to occur.
To achieve the above object, an aspect of the present invention provides an ash balance adjusting method, the method comprising:
s1, according to a correction curve L i Acquiring a cyan, magenta and yellow mixed image, wherein i is an integer greater than or equal to 0;
s2, judging whether the cyan, magenta and yellow mixed image is in a gray balance state;
s3, if the cyan, magenta and yellow mixed images are not in a gray balance state, respectively adjusting the overall percentages of the cyan, magenta and yellow channels, and performing re-fitting and smoothing processing on initial reference curve data according to the adjustment amplitude values of the overall percentages of the cyan, magenta and yellow channels to obtain new reference curve data;
s4, according to the new reference curveData Generation of a New calibration Curve L i+1 ；
S5, iteratively adjusting gray balance until the obtained cyan, magenta and yellow three-color mixed image is in a gray balance state, wherein i = i + 1;
wherein before the step S1, the method further comprises:
acquiring actual curve data formed by density values or lab values of a plurality of color blocks of each color map in a standard map and an initial reference curve formed by arranging a plurality of color blocks of the same number at equal intervals according to the density values of the color blocks in each color map;
carrying out linear fitting on the actual curve data and the initial reference curve data to obtain an initial correction curve L 0 。
Further, the re-fitting of the initial reference curve data according to the adjustment amplitude values of the overall percentages of the cyan, magenta and yellow channels comprises:
re-fitting the initial reference curve data according to the overall percentage adjustment amplitude value of a certain color to obtain the adjusted data of each color block in the certain color, wherein the fitting formula is as follows:
Data_new = Data_old*(1+A)；
data _ old is the initial reference curve Data of a color block in a color, data _ new is the adjusted Data of the color block, and a is the adjustment amplitude value of the whole percentage of the color.
Further, the smoothing the initial reference curve data according to the adjustment amplitude values of the overall percentages of the cyan, magenta, and yellow channels to obtain new reference curve data includes:
determining the number N of color blocks needing smoothing;
and smoothing the N color blocks to generate new reference curve data.
Further, the determining the number N of color blocks to be smoothed includes:
counting the number n of color blocks of which the adjusted data of each m color blocks of a certain color is larger than the maximum value of the initial reference curve;
calculating the number N =2 Xn-1 of color blocks needing smoothing according to the number N of the color blocks;
and selecting N color blocks from the color block numbers from large to small according to the number N of the color blocks to obtain the color block numbers needing smoothing treatment.
Further, the smoothing processing on the N color blocks to generate new reference curve data specifically includes:
by the smoothing formula:
f (x) _ new = [ f (x-r) + f (x-r + 1) + 8230) + f (x + r-1) + f (x + r) ]/(2r + 1) carries out smoothing treatment on the N color blocks; after the smooth data are obtained, generating new reference curve data;
wherein, x represents the color block number of a certain color, f (x) represents the density value corresponding to the color block, r is a natural number, and f (x) _ new represents the density value after the color block is smoothed.
Further, when the adjusting amplitude value is in the range of-1 to 0, re-fitting the initial reference curve data according to the adjusting amplitude value to obtain a new reference data curve without data smoothing;
and when the adjusting amplitude value is in the range of 0 to 1, re-fitting the initial reference curve data according to the adjusting amplitude value, and smoothing the fitted data to obtain the new reference data curve.
Further, before the obtaining of the cyan, magenta and yellow color mixture according to the initial calibration curve, the method further includes:
generating actual curve data;
and carrying out linear fitting on the actual curve data and the initial reference curve data to obtain an initial correction curve.
Further, the generating actual curve data includes:
obtaining the density value of each color block by scanning m color blocks of each color block in the calibration chart by adopting a colorimeter or color separation luminosity, and numbering each color block of each color according to the density value to obtain the actual curve data;
or, obtaining the lab value of each color block by scanning m color blocks of each color map in the calibration map by adopting a colorimeter or color separation luminosity, numbering each color block of each color according to the lab value, and performing difference processing on the lab value of the color block and the lab value of the white point to obtain actual curve data of the color block;
the calibration graph comprises a first color graph, a second color graph and a third color graph, wherein the first color graph, the second color graph and the third color graph respectively comprise m color blocks with gradually increasing gray levels.
In another aspect of the present invention, there is provided an ash balance adjusting apparatus comprising:
an acquisition module for acquiring the calibration curve L i Acquiring a cyan, magenta and yellow mixed image, wherein i is an integer greater than or equal to 0;
the judging module is used for judging whether the cyan, magenta and yellow mixed image is in a gray balance state or not;
the adjusting and processing module is used for respectively adjusting the overall percentage of the cyan, magenta and yellow channels if the cyan, magenta and yellow mixed graph is not in a gray balance state, and performing re-fitting and smoothing processing on the initial reference curve data according to the adjusting amplitude values of the overall percentages of the cyan, magenta and yellow channels to obtain new reference curve data;
a generating module for generating a new correction curve L according to the new reference curve data i+1 ；
And the circulating module is used for controlling the acquiring module, the judging module, the adjusting processing module and the generating module to iteratively adjust the gray balance, wherein i = i +1 until the cyan, magenta and yellow mixed images are in a gray balance state.
In another aspect, the present invention also provides a computer readable storage medium storing one or more programs, which are executable by one or more processors to implement the steps of any of the gray balance adjustment methods described above.
The gray balance adjusting method, the gray balance adjusting device and the computer readable storage medium provided by the invention continuously use a linear printing basis to control and analyze the input and the output of the printer, establish the corresponding relation between the gray value of the image color block and a density curve or a chroma difference curve by analyzing the actual curve of the gradually changed color block, set a reference curve, obtain a second correction curve according to the reference curve, and print according to the correction curve to realize gray balance. Through testing different inks, the invention has stronger robustness, and the overall color cast of the cyan, magenta and yellow mixed images is consistent without rainbow phenomenon. In addition, the gray balance processing can be automatically realized only by inputting the adjustment amplitude value in the adjustment process, the parameters of other color blocks do not need to be matched and calculated like the G7 process, and the operation is simple and quick.
Drawings
FIG. 1 is a flow chart of a method for ash balance adjustment according to the present invention;
FIG. 2 is a flow chart of a method for adjusting ash balance according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of an ash balance adjustment device according to a second embodiment of the present invention;
the implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
In the following description, suffixes such as "module", "component", or "unit" used to denote elements are used only for facilitating the explanation of the present invention, and have no specific meaning in itself. Thus, "module", "component" or "unit" may be used mixedly.
The present invention provides an ash balance adjustment method, as shown in fig. 1, the method comprising:
s1, acquiring a cyan, magenta and yellow mixed image according to an initial correction curve;
s2, judging whether the cyan, magenta and yellow mixed image is in a gray balance state;
s3, if the cyan, magenta and yellow mixed images are not in a gray balance state, respectively adjusting the overall percentages of the cyan, magenta and yellow channels, and performing re-fitting and smoothing processing on initial reference curve data according to the adjustment amplitude values of the overall percentages of the cyan, magenta and yellow channels to obtain new reference curve data;
s4, generating a second correction curve according to the new reference curve data;
and S5, acquiring a cyan, magenta and yellow three-color mixed image by using the second correction curve, judging whether the current cyan, magenta and yellow three-color mixed image is in a gray balance state, if the cyan, magenta and yellow three-color mixed image is not in the gray balance state, respectively adjusting the overall percentage of cyan, magenta and yellow three-color channels, and re-fitting and smoothing new reference curve data according to the adjustment amplitude values of the overall percentage of the cyan, magenta and yellow channels until the cyan, magenta and yellow three-color mixed image is in the gray balance state.
The gray balance adjusting method provided by the invention continuously uses a linear printing basis to control and analyze the input and output of the printer, establishes the corresponding relation between the gray value of the image color block and a density curve or a chromaticity difference curve by analyzing the actual curve of the gradually changed color block, sets a reference curve, obtains a second correction curve according to the reference curve, and prints according to the correction curve to realize gray balance. Through testing different inks, the invention has stronger robustness, and the overall color cast of the cyan, magenta and yellow mixed images is consistent without rainbow phenomenon. In addition, the gray balance processing can be automatically realized only by inputting the adjustment amplitude value in the adjustment process, the parameters of other color blocks do not need to be matched and calculated like the G7 process, and the operation is simple and quick.
The following describes in detail embodiments of the present invention.
Example one
An embodiment of the present invention provides an ash balance adjustment method, as shown in fig. 2, the method includes:
and S201, generating actual curve data.
The actual curve data is obtained by scanning m color blocks of each color block in the calibration chart by using a colorimeter or color separation luminosity to obtain the density value or lab value of each color block, and numbering each color block of each color according to the size of the density value or lab value. In this example m is 21.
Preferably, when the colorimeter or the color separation photometry scans the density values, the density value of each color block is the actual curve data, and when the lab value is obtained by scanning, the lab value of the color block is subjected to difference processing with the lab value of the white point to obtain the actual curve data of the color block.
In this embodiment, the calibration graph includes a first color graph, a second color graph, and a third color graph, where the first color graph, the second color graph, and the third color graph respectively include 21 color blocks with gradually increasing gray levels; the first, second and third color maps are cyan, magenta and yellow maps in CMYK mode.
S202, performing linear fitting on the actual curve data and the initial reference curve data to obtain a linear initial correction curve.
The data of the initial reference curve are obtained by arranging 21 color blocks at equal intervals according to the density values, and the density values of the 21 color blocks arranged at equal intervals are the data of the initial reference curve. In the CMYK mode, the density value of No. 0 color patch is 0, and the density value of No. 21 color patch is 100%.
S203, printing a three-color mixed image of cyan, magenta and yellow according to the linearized initial correction curve, and judging whether the gray balance state of the three-color mixed image is in neutral gray balance or not;
in this embodiment, whether the gray balance state of the three-color mixed graph is in neutral gray balance is mainly observed through instrument scanning or naked eyes.
And S204, when the three-color mixed graph of the cyan, the magenta and the yellow is not in a gray balance state, respectively adjusting the overall percentage of the three-color channels of the cyan, the magenta and the yellow.
The specific adjustment method is that when the three-color mixed image deviates from a certain color, the overall percentage of the color channel is reduced, and the overall percentages of the other two color channels are increased. For example, when the three color mixture is yellow, the overall percentage of the yellow channel is decreased and the overall percentage of the cyan and magenta channels is increased.
Preferably, the percentage of the maximum density in the cyan channel is set as a1, when a1 is less than or equal to 50%, the adjustment range of the cyan channel is greater than or equal to-a 1 and less than or equal to a1, and when a1 is greater than 50%, the adjustment range of the cyan channel is greater than or equal to-a 1 and less than or equal to 100%; setting the percentage of the maximum density in the magenta channel as b1, when b1 is less than or equal to 50%, the regulation range of the cyan channel is greater than or equal to-b 1 and less than or equal to b1, when b1 is greater than 50%, the regulation range of the cyan channel is greater than or equal to-b 1 and less than or equal to 100%; setting the percentage of the maximum density in the yellow channel as c1, when c1 is less than or equal to 50%, the regulation range of the cyan channel is greater than or equal to-c 1 and less than or equal to c1, and when c1 is greater than 50%, the regulation range of the cyan channel is greater than or equal to-c 1 and less than or equal to 100%;
s205, performing re-fitting and smoothing processing on the initial reference curve data according to the adjustment amplitude values of the overall percentages of the cyan, magenta and yellow channels to obtain new reference curve data;
preferably, when the adjustment amplitude value is in the range of-1 to 0, the initial reference curve data is re-fitted according to the adjustment amplitude value to obtain a new reference data curve, and data smoothing processing is not required. And when the adjusting amplitude value is in the range of 0 to 1, re-fitting the initial reference curve data according to the adjusting amplitude value, and smoothing the fitted data to obtain the new reference data curve.
Preferably, the initial reference curve data is re-fitted according to the overall percentage adjustment amplitude value of a certain color to obtain the adjusted data of each color block in the certain color, and the fitting formula is as follows:
Data_new = Data_old*(1+A)；
data _ old is the initial reference curve Data of a color block in a color, data _ new is the adjusted Data of the color block, and a is the adjustment amplitude value of the whole percentage of the color.
Preferably, the number N of color blocks of which the adjusted data of 21 color blocks of a certain color is greater than the maximum value of the initial reference curve is counted, the number N of the color blocks needing smoothing is calculated according to the number N of the color blocks, the number N of the color blocks needing smoothing is obtained by selecting the N color blocks from the number of the color blocks from small to large according to the number N of the color blocks, and the number N of the color blocks needing smoothing is averaged according to a smoothing formula.
The calculation formula of the number N of the smooth color blocks is as follows:
N=2×n-1
the smoothing formula is as follows:
f (x) _ new = [ f (x-r) + f (x-r + 1) + \8230, + f (x + r-1) + f (x + r) ]/(2r + 1) the N color blocks are subjected to smoothing treatment; after the smooth data are obtained, generating new reference curve data;
wherein, x represents the color block number of a certain color, f (x) represents the density value corresponding to the color block, r is a natural number, and f (x) _ new represents the density value after the color block is smoothed.
And S206, fitting and generating a second correction curve according to the new reference curve data, the actual curve data and the equidistant distribution data of the color block concentration.
And S207, repeating the steps S203-S206 until the cyan, magenta and yellow mixed image is in a gray balance state.
Illustratively, reprinting the cyan, magenta and yellow three-color mixed graph according to the second linear correction curve, and determining the gray balance state of the cyan, magenta and yellow three-color mixed graph; if the cyan, magenta and yellow mixed graph is in a neutral gray balance state, finishing the adjustment; and if the cyan, magenta and yellow mixed graph is not in a neutral gray balance state, repeating the adjustment of the steps S203-S206 until the cyan, magenta and yellow mixed graph is in a neutral gray balance state.
The gray balance adjusting method provided by the invention continuously uses a linear printing basis to control and analyze the input and output of the printer, establishes the corresponding relation between the gray value of the image color block and a density curve or a chromaticity difference curve by analyzing the actual curve of the gradually changed color block, sets a reference curve, obtains a second correction curve according to the reference curve, and prints according to the correction curve to realize gray balance. Through testing different inks, the invention has stronger robustness, and the overall color cast of a cyan, magenta and yellow mixed image is consistent without rainbow phenomenon. In addition, the gray balance processing can be automatically realized only by inputting the adjustment amplitude value in the adjustment process, the parameters of other color blocks do not need to be matched and calculated like the G7 process, and the operation is simple and quick.
Based on the above-mentioned various method embodiments, the present invention also provides the following apparatus embodiments.
Example two
An ash balance adjustment device 3 according to a second embodiment of the present invention is, as shown in fig. 3, an ash balance adjustment device 3 including:
an obtaining module 31, configured to obtain a cyan, magenta, and yellow mixed image according to the initial calibration curve;
a judging module 32, configured to judge whether the cyan, magenta, and yellow mixed image is in a gray balance state;
an adjusting processing module 33, configured to adjust overall percentages of the three-color channels of cyan, magenta, and yellow, respectively, if the cyan, magenta, and yellow mixed image is not in a gray balance state, and perform re-fitting and smoothing processing on the initial reference curve data according to adjustment amplitude values of the overall percentages of the cyan, magenta, and yellow channels, so as to obtain new reference curve data;
a generating module 34, configured to generate a second calibration curve according to the new reference curve data;
a circulation module 35, configured to control the acquiring module 31, the determining module 32, the adjusting processing module 33, and the generating module 34 to execute repeatedly until the cyan, magenta, and yellow mixed images are in a gray balance state.
In one embodiment, the adjustment processing module 33 includes:
a fitting module, configured to re-fit the initial reference curve data according to the overall percentage adjustment amplitude value of a certain color to obtain data after adjustment of each color block in the certain color, where the fitting formula is:
Data_new = Data_old*(1+A)；
data _ old is the initial reference curve Data of a color block in a color, data _ new is the adjusted Data of the color block, and a is the adjustment amplitude value of the whole percentage of the color.
The smoothing module is used for determining the number N of color blocks needing smoothing; smoothing the N color blocks according to a smoothing formula to generate new reference curve data;
the smoothing formula:
f (x) _ new = [ f (x-r) + f (x-r + 1) + \8230, + f (x + r-1) + f (x + r) ]/(2r + 1) the N color blocks are subjected to smoothing treatment; after smooth data are obtained, new reference curve data are generated;
wherein, x represents the color block number of a certain color, f (x) represents the density value corresponding to the color block, r is a natural number, and f (x) _ new represents the density value after the color block is smoothed.
EXAMPLE III
A third embodiment of the present invention provides a computer-readable storage medium, where one or more programs are stored, and the one or more programs are executable by one or more processors to implement the following steps:
s1, acquiring a cyan, magenta and yellow mixed image according to an initial correction curve;
s2, judging whether the cyan, magenta and yellow mixed image is in a gray balance state;
s3, if the cyan, magenta and yellow mixed images are not in a gray balance state, respectively adjusting the overall percentages of the cyan, magenta and yellow channels, and performing re-fitting and smoothing processing on initial reference curve data according to the adjustment amplitude values of the overall percentages of the cyan, magenta and yellow channels to obtain new reference curve data;
s4, generating a second correction curve according to the new reference curve data;
and S5, repeating the steps S1 to S4 until the cyan, magenta and yellow mixed image is in a gray balance state.
In one embodiment, the initial reference curve data refers to density values obtained by gradually increasing the gray scale by m color patches in an equally spaced arrangement, and the one or more programs are executable by one or more processors for performing the step of re-fitting the initial reference curve data according to the adjusted amplitude values of the respective global percentages of the cyan, magenta, and yellow channels to implement the steps of:
re-fitting the initial reference curve data according to the overall percentage adjustment amplitude value of a certain color to obtain the adjusted data of each color block in the certain color, wherein the fitting formula is as follows:
Data_new = Data_old*(1+A)；
data _ old is the initial reference curve Data of a certain color block in a certain color, data _ new is the adjusted Data of the color block, and a is the adjustment amplitude value of the whole percentage of the color.
In one embodiment, in the step of smoothing the initial reference curve data according to the adjusted amplitude values of the overall percentages of the cyan, magenta, and yellow channels to obtain new reference curve data, the one or more programs are executable by the one or more processors to implement the steps of:
determining the number N of color blocks needing smoothing;
and smoothing the N color blocks to generate new reference curve data.
In a specific embodiment, in the step of determining the number N of color blocks that need to be smoothed, the one or more programs may be executed by one or more processors to implement the following steps:
counting the number n of color blocks of which the data after the adjustment of the m color blocks of a certain color is larger than the maximum value of the initial reference curve;
calculating the number N =2 Xn-1 of color blocks needing smoothing according to the number N of the color blocks;
and selecting N color blocks from the color block numbers from large to small according to the number N of the color blocks to obtain the color block numbers needing smoothing treatment.
In one embodiment, in the step of smoothing the N color blocks to generate new reference curve data, the one or more programs may be executed by one or more processors to implement the following steps:
by the smoothing formula:
f (x) _ new = [ f (x-r) + f (x-r + 1) + \8230, + f (x + r-1) + f (x + r) ]/(2r + 1) the N color blocks are subjected to smoothing treatment; after the smooth data are obtained, generating new reference curve data;
wherein, x represents the color block number of a certain color, f (x) represents the density value corresponding to the color block, r is a natural number, and f (x) _ new represents the density value after the color block is smoothed.
In one embodiment, before the step of obtaining a three-color mixture of cyan, magenta, and yellow according to the initial calibration curve, the one or more programs are executable by the one or more processors to perform the steps of:
generating actual curve data;
and carrying out linear fitting on the actual curve data and the initial reference curve data to obtain an initial correction curve.
The gray balance adjusting method, the gray balance adjusting device and the computer readable storage medium provided by the invention continuously use a linear printing basis to control and analyze the input and the output of the printer, establish the corresponding relation between the gray value of the image color block and a density curve or a chroma difference curve by analyzing the actual curve of the gradually changed color block, set a reference curve, obtain a second correction curve according to the reference curve, and print according to the correction curve to realize gray balance. Through testing different inks, the invention has stronger robustness, and the overall color cast of a cyan, magenta and yellow mixed image is consistent without rainbow phenomenon. In addition, the gray balance processing can be automatically realized only by inputting the adjustment amplitude value in the adjustment process, the parameters of other color blocks do not need to be matched and calculated like the G7 process, and the operation is simple and quick.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a component of' 8230; \8230;" does not exclude the presence of another like element in a process, method, article, or apparatus that comprises the element.
The above-mentioned serial numbers of the embodiments of the present invention are merely for description and do not represent the merits of the embodiments.
Through the above description of the embodiments, those skilled in the art will clearly understand that the method of the above embodiments can be implemented by software plus a necessary general hardware platform, and certainly can also be implemented by hardware, but in many cases, the former is a better implementation manner. Based on such understanding, the technical solutions of the present invention may be embodied in the form of a software product, which is stored in a storage medium (such as ROM/RAM, magnetic disk, optical disk) and includes instructions for enabling a terminal (such as a mobile phone, a computer, a server, or a network device) to execute the method according to the embodiments of the present invention.
While the present invention has been described with reference to the particular illustrative embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but is intended to cover various modifications, equivalent arrangements, and equivalents thereof, which may be made by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (9)
1. A method of ash balance adjustment, the method comprising:
s1, according to a correction curve L i Acquiring a cyan, magenta and yellow mixed image, wherein i is an integer greater than or equal to 0;
s2, judging whether the cyan, magenta and yellow mixed image is in a gray balance state;
s3, if the cyan, magenta and yellow mixed images are not in a gray balance state, respectively adjusting the overall percentages of the cyan, magenta and yellow channels, and performing re-fitting and smoothing processing on initial reference curve data according to the adjustment amplitude values of the overall percentages of the cyan, magenta and yellow channels to obtain new reference curve data;
s4, generating a new correction curve L according to the new reference curve data i+1 ；
S5, iteratively adjusting gray balance until the obtained cyan, magenta and yellow three-color mixed image is in a gray balance state, wherein i = i + 1;
wherein before the step S1, the method further comprises:
acquiring actual curve data formed by density values or lab values of a plurality of color blocks of each color map in a standard map and an initial reference curve formed by arranging a plurality of color blocks of the same number at equal intervals according to the density values of the color blocks in each color map;
carrying out linear fitting on the actual curve data and the initial reference curve data to obtain an initial correction curve L 0 。
2. The gray balance adjustment method according to claim 1, wherein the initial reference curve data refers to density values of m color patches arranged by a density value size by gradually increasing gray scale, and the re-fitting of the initial reference curve data according to the adjustment amplitude values of the respective overall percentages of the cyan, magenta and yellow channels comprises:
re-fitting the initial reference curve data according to the overall percentage adjustment amplitude value of a certain color to obtain the adjusted data of each color block in the certain color, wherein the fitting formula is as follows:
Data_new = Data_old*(1+A)；
data _ old is the initial reference curve Data of a color block in a color, data _ new is the adjusted Data of the color block, and a is the adjustment amplitude value of the whole percentage of the color.
3. The gray balance adjustment method according to claim 2, wherein smoothing the initial reference curve data to obtain new reference curve data according to the adjustment amplitude values of the respective overall percentages of the cyan, magenta and yellow channels comprises:
determining the number N of color blocks needing smoothing;
and smoothing the N color blocks to generate new reference curve data.
4. The gray balance adjustment method according to claim 3, wherein the determining the number N of color patches that need to be smoothed comprises:
counting the number n of color blocks of which the adjusted data of each m color blocks of a certain color is larger than the maximum value of the initial reference curve;
calculating the number of color blocks N =2 xn-1 which needs to be smoothed according to the number N of the color blocks;
and selecting N color blocks from the color block numbers from large to small according to the number N of the color blocks to obtain the color block numbers needing smoothing treatment.
5. The gray balance adjustment method according to claim 3, wherein the smoothing of the N color patches to generate new reference curve data specifically comprises:
by the smoothing formula:
f (x) _ new = [ f (x-r) + f (x-r + 1) + 8230) + f (x + r-1) + f (x + r) ]/(2r + 1) carries out smoothing treatment on the N color blocks; after the smooth data are obtained, generating new reference curve data;
wherein, x represents the color block number of a certain color, f (x) represents the density value corresponding to the color block, r is a natural number, and f (x) _ new represents the density value after the color block is smoothed.
6. The ash balance adjustment method according to claim 1,
when the adjusting amplitude value is in the range of-1 to 0, re-fitting the initial reference curve data according to the adjusting amplitude value to obtain a new reference data curve without data smoothing;
and when the adjusting amplitude value is in the range of 0 to 1, re-fitting the initial reference curve data according to the adjusting amplitude value, and smoothing the fitted data to obtain the new reference data curve.
7. The gray balance adjustment method according to any one of claims 1 to 6, wherein said acquiring actual curve data made up of density values or lab values of a plurality of color patches of each color patch in a standard map comprises:
obtaining the density value of each color block by scanning m color blocks of each color block in the calibration chart by adopting a colorimeter or color separation luminosity, and numbering each color block of each color according to the density value to obtain the actual curve data;
or, obtaining the lab value of each color block by scanning m color blocks of each color map in the calibration map by adopting a colorimeter or color separation luminosity, numbering each color block of each color according to the lab value, and performing difference processing on the lab value of the color block and the lab value of the white point to obtain actual curve data of the color block;
the calibration graph comprises a first color graph, a second color graph and a third color graph, wherein the first color graph, the second color graph and the third color graph respectively comprise m color blocks with gradually increasing gray levels.
8. An ash balance adjustment device, comprising:
an acquisition module for acquiring the calibration curve L i Acquiring a cyan, magenta and yellow mixed image, wherein i is an integer greater than or equal to 0;
the judging module is used for judging whether the cyan, magenta and yellow mixed image is in a gray balance state or not;
the adjusting processing module is used for respectively adjusting the overall percentages of the cyan, magenta and yellow channels if the cyan, magenta and yellow mixed images are not in a gray balance state, and performing re-fitting and smoothing processing on initial reference curve data according to the adjusting amplitude values of the overall percentages of the cyan, magenta and yellow channels to obtain new reference curve data;
a generating module for generating a new correction curve L according to the new reference curve data i+1 ；
And the circulating module is used for controlling the acquiring module, the judging module, the adjusting processing module and the generating module to iteratively adjust the gray balance, wherein i = i +1 until the cyan, magenta and yellow mixed images are in a gray balance state.
9. A computer readable storage medium, storing one or more programs, the one or more programs being executable by one or more processors to perform the steps of the gray balance adjustment method of any one of claims 1-7.
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