Spectrum matching-based spot color production conversion method from digital proofing to offset printing

Abstract

The invention provides a spectrum matching-based spot color production switching method from digital proofing to offset printing. The method comprises the following steps of: obtaining target spectrum characteristic data; color matching processing is conducted on the target spectrum data through a preset ink optical characteristic database, offset printing color matching data are obtained, and the offset printing color matching data are base ink types and base ink combinations needed for ink blending; on the basis of a preset spectrum matching algorithm, blending calculation processing is conducted on the target spectrum characteristic data, offset printing matching data are obtained, and the offset printing matching data are used for determining the type of the base ink or the dosage proportion of the base ink in the base ink combination; and on the basis of the offset printing color matching data and the offset printing matching data, generating a corresponding offset printing result to realize seamless, high-fidelity and metamerism-free spot color conversion from digital proofing to offset printing production, so that the dependence on artificial experience is reduced, the proofing cost is reduced, and the production efficiency and the color consistency are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of printing process, and in particular to a special color transfer production method from digital proofing to offset printing based on spectral matching. BACKGROUND

[0002] In the field of packaging printing, special color printing has become a key link in the quality control of high-end packaging products due to its strict requirements on color consistency and visual effect. With the development of digital plate making and digital printing technology, digital proofing has gradually become an important link before special color printing. Digital proofing simulates the target special color effect through the superposition of CMYK four-color or even multi-color inks; while in the actual offset printing production process, the pre-prepared special color ink is directly used for printing. Due to the significant differences in ink system, color forming mechanism and the like between the two processes, it is difficult to effectively guarantee the color consistency between the digital proofing result and the offset printing product.

[0003] At present, in the special color transfer production process from digital proofing to offset printing based on spectral matching, it still mainly relies on the experience of offset printing operators to repeatedly adjust and test print the special color ink formula in order to restore the color effect of the digital proofing manuscript as much as possible. However, this method not only has a long debugging period and large consumption of ink and paper, but also has a strong dependence on the experience level of the operators, and it is difficult to form a standardized and reproducible process flow, resulting in low production efficiency and difficulty in long-term guarantee of color stability and consistency.

[0004] To solve the above problems, in the prior art, there are computer color matching methods for offset special color inks, which calculate the initial ink formula through spectral matching, and obtain the final formula result combined with color difference correction. However, such methods mainly focus on the offset special color matching process itself, usually taking offset samples or target color samples as reference objects, and do not fully consider the differences in color rendering mechanism, ink optical properties and substrate response between digital proofing and offset printing production, making it difficult to realize high-fidelity and seamless special color transfer production from digital proofing to offset printing based on spectral matching, especially in a multi-light source environment, which is still prone to metamerism.

[0005] Therefore, the existing special color transfer production technology from digital proofing to offset printing based on spectral matching still has the problem of being unable to realize stable color transmission between digital proofing and offset printing production under different color rendering mechanisms. SUMMARY

[0006] The application provides a special color transfer production method based on spectral matching of digital proofing to offset printing, to solve the problem that the existing special color transfer production method based on spectral matching of digital proofing to offset printing cannot realize stable color transmission between digital proofing and offset printing production under different color rendering mechanism conditions.

[0007] In a first aspect, the application provides a special color transfer production method based on spectral matching of digital proofing to offset printing, which comprises the following steps: acquiring target spectral feature data; performing color matching processing on the target spectral data through a preset ink optical property database to obtain offset printing color matching data, wherein the offset printing color matching data is the required base ink type and base ink combination for ink matching; performing matching calculation processing on the target spectral feature data based on a preset spectral matching algorithm to obtain offset printing matching ratio data, wherein the offset printing matching ratio data is used to determine the usage proportion of each base ink in the base ink type or the base ink combination; generating corresponding offset printing results based on the offset printing color matching data and the offset printing matching ratio data.

[0008] Optionally, the acquiring target spectral data comprises: acquiring target special color data and performing digital proofing processing on the target special color to generate a target special color block; acquiring spectral reflectance data of the target special color block through a spectrophotometer to obtain the target spectral feature data.

[0009] Optionally, before the step of performing color matching processing on the target spectral data through a preset ink optical property database to obtain offset printing color matching data, the method further comprises: acquiring a standard sample color block set of offset printing ink; performing spectral measurement on each standard sample color block in the standard sample color block set of offset printing ink to obtain corresponding spectral reflectance data of each standard sample color block under a preset printing medium; performing standardization processing on the spectral reflectance data to generate corresponding ink optical property parameters; storing the ink optical property parameters and the corresponding standard sample color blocks in association to form the preset ink optical property database.

[0010] Optionally, the performing color matching processing on the target spectral data through a preset ink optical property database to obtain offset printing color matching data comprises: The target spectrum data is imported into the preset ink optical characteristic database for similarity matching processing, so as to obtain a target spectrum similarity corresponding to each standard sample color block in the preset ink optical characteristic database and the target spectrum data; Based on the target spectrum similarity, the offset color matching data is determined.

[0011] Optionally, the determination of the offset color matching data based on the target spectrum similarity comprises: When the target spectrum similarity between the standard sample color block and the target spectrum data is greater than or equal to a first preset spectrum similarity, it is determined whether the standard sample color block satisfies the target spectrum requirement alone; If yes, the base ink type corresponding to the standard sample color block is determined as the offset color matching data; If no, a plurality of standard sample color blocks with a target spectrum similarity greater than or equal to a second preset spectrum similarity threshold value are screened out as the base ink combination, and the base ink combination is determined as the offset color matching data.

[0012] Optionally, the adjustment and calculation processing of the target spectrum feature data based on the preset spectrum matching algorithm comprises: The offset color matching data is imported into the preset spectrum matching algorithm, and spectrum difference data between the offset color matching data and the target spectrum feature data is calculated; Based on the spectrum difference data, the offset color matching data is adjusted and processed to obtain the offset ratio data.

[0013] Optionally, after the generation of the corresponding offset printing result based on the offset color matching data and the offset ratio data, the method further comprises: A color difference value between the offset printing result and the target spot color block is calculated; If the color difference value is greater than a preset color difference threshold value, then the target spectrum data and the offset measured spectrum are subjected to difference analysis to generate spot color deviation features; The spot color deviation features are imported into the preset spectrum matching-based digital proofing to offset printing spot color production algorithm for spot color iteration processing, and the offset printing result is updated until the color difference value is less than or equal to the preset color difference threshold value.

[0014] In a second aspect, the present application further provides a spectrum matching-based digital proofing to offset printing spot color production device, which comprises: An acquisition module is configured to acquire target spectrum data; The matching module is configured to perform color matching processing on the target spectrum data based on a preset ink optical property database to obtain offset printing color matching data. The computing module is configured to perform adjustment calculation processing on the target spectrum feature data based on a preset spectrum matching algorithm to obtain offset printing ratio data. The production module is configured to generate corresponding offset printing results based on the offset printing color matching data and the offset printing ratio data.

[0015] In a fourth aspect, the present application provides a computer readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps of the method for converting spot color from digital proofing to offset printing based on spectrum matching are implemented.

[0016] The present application obtains target spectrum feature data, performs color matching processing on the target spectrum data based on a preset ink optical property database to obtain offset printing color matching data, which is the required base ink type and base ink combination for ink adjustment, performs adjustment calculation processing on the target spectrum feature data based on a preset spectrum matching algorithm to obtain offset printing ratio data, which is used to determine the dosage proportion of each base ink in the base ink type or the base ink combination, and generates corresponding offset printing results based on the offset printing color matching data and the offset printing ratio data to realize seamless, high-fidelity and metamerism-free spot color conversion from digital proofing to offset printing, reduce the dependence on manual experience, reduce proofing costs, and improve production efficiency and color consistency. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort.

[0018] Figure 1 is a flowchart of a method for converting spot color from digital proofing to offset printing based on spectrum matching provided by an embodiment of the present application; Figure 2 is a structural schematic diagram of a device for converting spot color from digital proofing to offset printing based on spectrum matching provided by an embodiment of the present application; Figure 3 is a structural schematic diagram of an electronic device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0019] With reference to the drawings and embodiments of the present application, the technical solutions in the embodiments of the present application will be described clearly and completely. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of the present application.

[0020] As shown in Figure 1 , Figure 1 is a flowchart of a digital proofing to offset printing spot color transfer method based on spectrum matching provided by an embodiment of the present application. The digital proofing to offset printing spot color transfer method based on spectrum matching comprises the following steps: 101, obtaining target spectrum feature data.

[0021] In the embodiment of the present application, the above-mentioned digital proofing to offset printing spot color transfer method based on spectrum matching can be applied to a digital proofing to offset printing spot color transfer platform based on spectrum matching. The digital proofing to offset printing spot color transfer platform based on spectrum matching has functions of image data processing, image data transceiving, and image data memory storage, and can be constructed based on a server or a server cluster. The server or the server cluster can be an electronic device with image data processing capability.

[0022] The digital proofing to offset printing spot color transfer platform based on spectrum matching further has a database module. The database module can form a spot color database by continuously adding new color ink formulas as a group set according to ink series and substrates, and update and iterate the spectrum feature data content corresponding to subsequent offset printing spot color transfer according to the data content in the spot color database.

[0023] The target spectrum feature data is used to represent the optical reflection characteristics of the target spot color under a preset spectrum measurement condition. It can be represented in the form of spectrum data with reflectivity changing with wavelength, or in the form of spectrum feature parameters obtained by processing spectrum reflectivity data. The target spectrum feature data can reflect the spectrum distribution characteristics of the target spot color in different wavelength intervals, and is used as an input basis for color matching and ink dispensing calculation.

[0024] Further, the target spot color can be an expected color reproduced by offset printing, which is derived from a design file, a brand color standard, or a digital proofing result, and is used as a target object for digital proofing to offset printing spot color transfer and ink dispensing based on spectrum matching. The target spot color can form a corresponding color sample through digital proofing, or exist in the form of digital color values, and is further converted into a color expression form for spectrum analysis.

[0025] 102. Color matching the target spectral data with the preset ink optical property database to obtain the offset color matching data.

[0026] In the embodiments of the present application, the preset ink optical property database can be a structured data set for characterizing the optical properties of offset ink. Specifically, it includes but is not limited to spectral reflectance data of base ink formed under preset printing medium conditions, optical property parameters obtained by processing the spectral reflectance data, identification information corresponding to the ink type, and basic condition information related to spectral measurement. The ink optical property database can be constructed by performing spectral measurement on standard sample color blocks and processing the measurement results, and is used to support color matching and adjustment calculation between target spectral data and offset ink.

[0027] In a possible embodiment, the color matching process can be a process of determining the base ink type or base ink combination involved in ink adjustment based on the spectral similarity relationship between the target spectral feature data and the corresponding spectral data in the ink optical property database. The color matching process compares the difference between different ink spectral data and the target spectral feature data, selects the ink composition scheme with higher matching degree with the target spectral feature data, and thus provides a limited base ink range for subsequent adjustment calculation processing.

[0028] The above-mentioned offset color matching data is the base ink type and base ink combination required for ink adjustment, which can be used to represent the information set of the ink composition required for offset spot color adjustment, and is used to indicate the base ink type or base ink combination composed of multiple base inks involved in ink adjustment. Specifically, the above-mentioned base ink type is used to represent the type identification of a single offset base ink, which corresponds to a single ink category involved in spot color adjustment; the base ink combination is used to represent an ink set composed of two or more different base ink types, which is used to jointly participate in ink adjustment when a single base ink cannot meet the requirements of the target spot color.

[0029] More specifically, the offset color matching data is used to limit the base ink range for ink adjustment, without involving the specific usage ratio of each base ink, so as to further determine the corresponding matching relationship in the subsequent adjustment calculation processing based on the base ink range. By distinguishing the offset color matching data from the offset matching data, the clarity of the digital proofing to offset spot color production process based on spectral matching and the stability of the adjustment calculation can be improved.

[0030] 103. Adjustment calculation processing of the target spectral feature data based on the preset spectral matching algorithm to obtain the offset matching data.

[0031] In the embodiments of the present application, the preset spectrum matching algorithm can be a calculation method for calculating and optimizing the difference between the target spectrum feature data and the ink-related spectrum data, which compares the spectrum features in different wavelength intervals, evaluates the color matching degree, and determines the corresponding ink blending result under the condition of meeting the preset constraint condition.

[0032] Specifically, the spectrum matching algorithm can be implemented based on spectrum difference measurement, spectrum shape consistency evaluation, or a combination of the two, to support base ink combination selection and base ink usage ratio calculation, thereby improving the accuracy and stability of the digital proofing to offset printing process of the spot color based on spectrum matching. Based on the offset printing color matching data and the offset printing ratio data, the corresponding offset printing result is generated.

[0033] In the embodiments of the present application, the offset printing ratio data is used to represent the proportion of each base ink participating in ink blending in the overall ink system. It reflects the relative usage relationship between different base inks in a preset proportion representation manner. Specifically, the offset printing ratio data is used to guide the actual blending of offset spot color ink, so that the base ink combination forms an offset printing result that matches the target spectrum feature data under the predetermined blending condition.

[0034] In one possible embodiment, the above blending calculation process can be a process of calculating and adjusting the usage ratio of each base ink according to the difference between the target spectrum feature data and the predicted offset printing spectrum result within a limited base ink type or base ink combination range. The blending calculation process compares the spectrum results corresponding to different base ink usage ratios, gradually optimizes the proportion relationship between the base inks, and makes the calculated offset printing spectrum result approach the target spectrum feature data, thereby generating offset printing ratio data for guiding the actual ink blending.

[0035] 104、Based on the offset printing color matching data and the offset printing ratio data, the corresponding offset printing result is generated.

[0036] In the embodiments of the present application, the offset printing result can be a spot color printing sample formed by offset printing on a preset printing medium based on the determined base ink type or base ink combination and the corresponding base ink usage ratio. The offset printing result is used to intuitively reflect the actual color rendering effect after ink blending, and can be used as an object for comparison and verification with the target spot color to evaluate the accuracy and stability of the digital proofing to offset printing process of the spot color based on spectrum matching.

[0037] In a possible embodiment, according to the determined color matching data and color ratio data of offset printing, first, a corresponding base ink is selected according to the base ink type or base ink combination indicated by the color matching data of offset printing; then, the amount ratio of each base ink in the ink matching process is determined according to the color ratio data of offset printing, each base ink is weighed and fully mixed to obtain the spot color ink used for offset printing. Subsequently, the matched spot color ink is loaded into the offset printing equipment, and the offset printing operation is performed under the preset printing medium and printing condition, so as to form the corresponding spot color printing pattern on the printing medium as the offset printing result. By limiting the ink composition range based on the color matching data of offset printing and accurately controlling the amount ratio of each base ink based on the color ratio data of offset printing, the generated offset printing result can stably reproduce the spectral characteristics of the target spot color under the predetermined condition, and a reliable printing sample is provided for subsequent color difference evaluation and iterative correction.

[0038] The application obtains target spectral feature data; performs color matching processing on the target spectral data through a preset ink optical property database to obtain color matching data of offset printing, the color matching data of offset printing being the base ink type and base ink combination required for ink matching; performs matching calculation processing on the target spectral feature data based on a preset spectral matching algorithm to obtain color ratio data of offset printing, the color ratio data of offset printing being used to determine the amount ratio of each base ink in the base ink type or base ink combination; and based on the color matching data and color ratio data of offset printing, generates a corresponding offset printing result to realize seamless, high-fidelity and metamerism-free spot color production from digital proofing to offset printing, reduce the dependence on manual experience, reduce the proofing cost, and improve the production efficiency and color consistency.

[0039] Optionally, in the step of obtaining target spectral feature data, target spot color data can also be obtained, and the target spot color is subjected to digital proofing processing to generate a target spot color block; and spectral reflectance data of the target spot color block is collected by a spectrophotometer to obtain the target spectral feature data.

[0040] In the embodiment of the application, the above-mentioned target spot color data can be color information used to represent an expected spot color effect, and the source thereof can include color definition in a design file, standard spot color information specified by a brand or a customer, or color data generated by a digital proofing process. The target spot color data is used to describe a color target that needs to be reproduced in the offset printing result, and can be further used as a basic input for obtaining the target spectral feature data to support subsequent color matching, ink matching and printing result verification processes.

[0041] The above-described spectrophotometer can be an optical measurement device for measuring the spectral reflectance characteristics of a color sample within a predetermined wavelength range, which can obtain the reflectance or equivalent spectral data of the color sample at different wavelengths. The spectrophotometer can perform spectral measurement on the target spot color patch or the offset printing result under predetermined measurement conditions to obtain spectral characteristic data for color matching and dispensing calculation, thereby providing an objective and quantifiable optical data basis for the spot color transfer process from digital proofing to offset printing based on spectral matching.

[0042] The above-mentioned digital proofing process refers to a process of generating a color sample on a specified proofing medium through a digital output device based on digital color data. This process is used to simulate the visual effect of the target spot color in a digital manner before actual printing production, so that the target color can be presented in the form of a physical patch. Through the digital proofing process, color information originally existing in digital form can be converted into measurable and comparable color samples, thereby providing a reference basis for spectral measurement, color matching, and subsequent ink dispensing.

[0043] In one possible embodiment, target spot color data representing the expected spot color effect is first obtained. The target spot color data can come from design files, brand standard color information, or customer-specified color data. Based on the obtained target spot color data, a digital proofing process is performed on the target spot color to generate a corresponding target spot color patch under predetermined proofing device and proofing medium conditions. Subsequently, a spectrophotometer is used to perform spectral measurement on the generated target spot color patch to collect spectral reflectance data of the target spot color patch within multiple wavelength intervals under predetermined measurement conditions. By organizing and processing the collected spectral reflectance data, target spectral characteristic data for subsequent color matching and dispensing calculation is obtained. In this way, the target spot color can be objectively characterized in the form of spectral characteristic data, providing a stable and quantifiable input basis for the spot color transfer method from digital proofing to offset printing based on spectral matching.

[0044] Optionally, before the step of performing color matching processing on the target spectral data through the predetermined ink optical characteristic database to obtain offset dispensing data, the method further includes: obtaining a set of standard sample patches of offset ink; performing spectral measurement on each standard sample patch in the set of standard sample patches of offset ink to obtain corresponding spectral reflectance data of each standard sample patch under a predetermined printing medium; performing standardization processing on the spectral reflectance data to generate corresponding ink optical characteristic parameters; and storing the ink optical characteristic parameters in association with the corresponding standard sample patches to form the predetermined ink optical characteristic database.

[0045] In the embodiment of the present application, the standard sample color block set of the offset ink can be a set of color samples formed by different base inks used for offset spot color matching under preset printing medium and preset printing conditions. The standard sample color block set is used to characterize the basic color rendering characteristics of each base ink under actual offset printing conditions, and serves as a reference sample source for constructing the ink optical characteristic database and performing color matching processing.

[0046] In the embodiment of the present application, the ink optical characteristic parameter can be parameter information used to characterize the optical performance of the offset ink under preset printing medium conditions, specifically including but not limited to spectral reflectance data reflecting the reflection characteristics of the ink to light of different wavelengths, spectral feature parameters processed from the spectral reflectance data, comprehensive color feature parameters used to describe the overall optical performance of the ink, and auxiliary identification information related to the color rendering characteristics of the ink. The above-mentioned ink optical characteristic parameters are used to establish the correspondence between the ink and its spectral response, and provide basic data support for color matching processing and matching calculation processing.

[0047] In a possible embodiment, before performing color matching processing on the target spectral data through the ink optical characteristic database, a standard sample color block set of the offset ink used for offset spot color matching is first obtained. The standard sample color block set can be prepared by different base inks under preset printing medium and preset printing conditions, and is used to characterize the basic color rendering characteristics of each base ink under offset printing conditions. Then, spectral measurement is performed on each standard sample color block in the standard sample color block set, and spectral reflectance data of the standard sample color block on the preset printing medium is collected under uniform measurement conditions. Through the spectral measurement process, spectral reflectance information reflecting the optical response characteristics of different base inks in each wavelength interval can be obtained. After obtaining the spectral reflectance data, the spectral reflectance data is standardized to eliminate the influence of measurement environment difference, printing medium difference or measurement noise on the spectral data, and to generate ink optical characteristic parameters capable of stably characterizing the optical characteristics of the ink. The ink optical characteristic parameters are used to describe the optical performance form of the corresponding standard sample color block under preset conditions. Finally, the generated ink optical characteristic parameters are associated with the corresponding standard sample color block and stored to form a preset ink optical characteristic database. The ink optical characteristic database constructed through the above-mentioned manner can serve as a basic data source for subsequent color matching processing and ink matching calculation of the target spectral data.

[0048] Optionally, the target spectral data is subjected to color matching processing through the preset ink optical characteristic database to obtain offset color matching data, including: importing the target spectral data into the preset ink optical characteristic database for similarity matching processing to obtain a target spectral similarity corresponding to the target spectral data and each standard sample color block in the preset ink optical characteristic database; and determining the offset color matching data based on the target spectral similarity.

[0049] In the embodiments of the present application, the target spectrum similarity can be an evaluation index used to characterize the closeness between the target spectrum feature data and the corresponding spectrum data, which reflects the similarity of the spectrum distribution characteristics of the two in multiple wavelength intervals. The target spectrum similarity can be comprehensively evaluated based on the overall shape of the spectrum, the spectrum variation trend or the spectrum difference degree, which is used to judge the matching degree of different color samples at the spectrum level, thereby providing a basis for determining the offset printing color matching data.

[0050] In a possible embodiment, after the construction of the ink optical property database is completed, the obtained target spectrum feature data is imported into the preset ink optical property database as matching input. The ink optical property database stores ink optical property parameters corresponding to multiple standard sample color blocks, and each ink optical property parameter is used to characterize the spectrum performance of the corresponding standard sample color block under the condition of the preset printing medium. Then, the target spectrum feature data is compared with the ink optical property parameters corresponding to each standard sample color block in the ink optical property database one by one, and the matching degree between the target spectrum feature data and each standard sample color block is calculated by comparing the spectrum features in different wavelength intervals. Based on the above comparison result, the target spectrum similarity corresponding to the target spectrum feature data and each standard sample color block in the ink optical property database is obtained respectively. Through the similarity matching process, a one-to-one correspondence between the target spectrum feature data and each standard sample color block can be formed, which provides a quantitative basis for determining the offset printing color matching data based on the target spectrum similarity.

[0051] Optionally, the determination of the offset printing color matching data based on the target spectrum similarity comprises: When the target spectrum similarity between the standard sample color block and the target spectrum data is greater than or equal to a first preset spectrum similarity, it is determined whether the standard sample color block satisfies the target spectrum requirement alone; If yes, the base ink type corresponding to the standard sample color block is determined as the offset printing color matching data; If no, multiple standard sample color blocks whose target spectrum similarity with the target spectrum data is greater than or equal to a second preset spectrum similarity threshold are screened out as a base ink combination, and the base ink combination is determined as the offset printing color matching data.

[0052] In the embodiment of the present application, the first preset spectral similarity can be a judgment criterion for determining whether a single standard sample color block can meet the target spot color requirement, which is used to reflect the matching degree between the target spectral feature data and the spectral data corresponding to the single standard sample color block at the spectral level. The first preset spectral similarity is used as a judgment condition for a higher matching requirement. When the target spectrum and a certain standard sample color block reach the matching degree in terms of spectral distribution characteristics, it can be considered that the base ink corresponding to the standard sample color block has the feasibility of being used for flexographic spot color matching alone.

[0053] In the embodiment of the present application, the second preset spectral similarity can be a judgment criterion for screening standard sample color blocks participating in the construction of a base ink combination, which is used to reflect the closeness between the target spectral feature data and the spectral data corresponding to multiple standard sample color blocks at the spectral level. The second preset spectral similarity is used as a lower matching requirement relative to the first preset spectral similarity, which is used to determine several base ink candidates having a higher correlation with the target spectrum in terms of spectral characteristics when a single standard sample color block cannot meet the target spot color requirement, so as to construct a base ink combination for flexographic spot color matching.

[0054] In a possible embodiment, after obtaining the target spectral similarity between the target spectral data and the spectral data corresponding to each standard sample color block, the target spectral similarity corresponding to each standard sample color block is first compared with the first preset spectral similarity. When the target spectral similarity between a certain standard sample color block and the target spectral data is greater than or equal to the first preset spectral similarity, it is determined that the standard sample color block has a higher matching degree at the spectral level, and it is further determined whether the standard sample color block can meet the target spectral requirement alone.

[0055] In the judgment process, whether a single base ink can realize the spectral reproduction of the target spot color under the preset printing condition can be determined based on the overall matching between the spectral characteristics corresponding to the standard sample color block and the target spectral feature data. When the judgment result shows that the standard sample color block can meet the target spectral requirement alone, the base ink type corresponding to the standard sample color block is determined as the flexographic color matching data, which is used for subsequent ink matching.

[0056] When the judgment result shows that the standard sample color block cannot meet the target spectral requirement alone, or there is no target spectral similarity of any standard sample color block reaching the first preset spectral similarity, the base ink combination determination process is entered. In this case, multiple standard sample color blocks having a target spectral similarity with the target spectral data greater than or equal to the second preset spectral similarity are screened from the standard sample color blocks, and a base ink combination is constructed according to the base ink types corresponding to the screened standard sample color blocks. Subsequently, the base ink combination is determined as the flexographic color matching data, which is used to limit the range of base inks participating in ink matching in subsequent matching calculation processing.

[0057] By the above hierarchical determination mode, when the target spot color is relatively simple, the single base ink scheme is preferred, and when the target spot color is relatively complex, the multi-base ink combination scheme is automatically switched, so that the stability and implementability of the offset spot color matching are improved while the color matching accuracy is ensured.

[0058] After the step of generating the corresponding offset printing result based on the offset color matching data and the offset matching ratio data, further comprising: calculating the color difference value between the offset printing result and the target spot color block; If the color difference value is greater than the preset color difference threshold, then the target spectral data and the offset measured spectrum are analyzed for differences to generate a spot color deviation feature; The spot color deviation feature is introduced into a preset digital proofing to offset spot color conversion algorithm based on spectral matching for spot color iterative processing, and the offset printing result is updated until the color difference value is less than or equal to the preset color difference threshold.

[0059] In the embodiments of the present application, the spot color deviation feature can be a difference feature information for characterizing the difference between the offset printing result and the target spot color in spectral or color performance, which is used to reflect the deviation of the two in overall color rendering effect or spectral distribution characteristics. The spot color deviation feature can be obtained by difference analysis between the target spectral feature data and the offset measured spectral data, which is used to describe the color deviation trend or spectral difference direction generated in the digital proofing to offset spot color conversion process based on spectral matching, and serves as a reference basis for subsequent spot color iterative processing and color matching correction.

[0060] In the embodiments of the present application, the preset color difference threshold can be a determination reference for determining whether the color matching degree between the offset printing result and the target spot color meets the expected requirements, which is used to reflect the allowed difference range of the two in the overall color perception level. The color difference threshold is used as an evaluation condition for the digital proofing to offset spot color conversion result based on spectral matching, when the color difference between the offset printing result and the target spot color does not exceed the threshold, it can be considered that the current digital proofing to offset spot color conversion result based on spectral matching meets the application requirements; when the color difference exceeds the threshold, further deviation analysis and iterative correction processing is triggered.

[0061] In one possible embodiment, after generating the offset printing result, the color consistency of the offset printing result and the target spot color block is evaluated. Specifically, under a preset measurement condition, the color of the color area corresponding to the offset printing result and the target spot color block is measured respectively, and based on the measurement result, the color difference value between the offset printing result and the target spot color block is calculated, which is used to characterize the difference degree of the two in color performance.

[0062] When the calculated color difference value is greater than the preset color difference threshold, it is determined that the current offset printing result does not meet the expected requirement of the spectral matching-based digital proofing to offset printing. In this case, the target spectral data and the measured spectral data corresponding to the offset printing result are analyzed for differences, the spectral distribution characteristics of the two in different wavelength intervals are compared, the characteristic information reflecting the offset direction or offset trend of the spot color is extracted, and the spot color deviation feature is generated.

[0063] Subsequently, the generated spot color deviation feature is imported as input data into a preset spectral matching-based digital proofing to offset printing algorithm, the ink matching process is iteratively processed based on the spot color deviation feature, the base ink composition or base ink usage proportion is adjusted accordingly, and the offset printing result is regenerated based on the adjusted result. The color difference value between the updated offset printing result and the target spot color patch is calculated again, and the calculation result is compared with the preset color difference threshold.

[0064] Through repeated difference analysis and iterative processing, the color difference value between the offset printing result and the target spot color patch is less than or equal to the preset color difference threshold, thereby completing the iterative convergence of the spectral matching-based digital proofing to offset printing process, and the final obtained offset printing result meets the matching requirement of the target spot color.

[0065] As shown in Figure 2 The present application also provides a spectral matching-based digital proofing to offset printing device 200, which comprises: An acquisition module 201 for acquiring target spectral data; A matching module 202 for performing color matching processing on the target spectral data through a preset ink optical property database to obtain offset printing color matching data; A calculation module 203 for performing matching calculation processing on the target spectral feature data based on a preset spectral matching algorithm to obtain offset printing matching ratio data; A production module 204 for generating corresponding offset printing results based on the offset printing color matching data and the offset printing matching ratio data.

[0066] Optionally, the acquisition module 201 comprises: A first acquisition sub-module for acquiring target spot color data and performing digital proofing processing on the target spot color to generate a target spot color patch; A collection sub-module for collecting spectral reflectance data of the target spot color patch through a spectrophotometer to obtain the target spectral feature data.

[0067] Optionally, the matching module 202 comprises: a color acquisition module, configured to acquire a set of standard sample color blocks of offset ink; a measurement module, configured to perform spectral measurement on each standard sample color block in the set of standard sample color blocks of the offset ink, to obtain corresponding spectral reflectance data of each standard sample color block under a preset printing medium; a processing module, configured to perform standardization processing on the spectral reflectance data, to generate corresponding ink optical characteristic parameters; a forming module, configured to store the ink optical characteristic parameters in association with the corresponding standard sample color blocks, to form the preset ink optical characteristic database.

[0068] Optionally, the matching module 202 includes: an importing submodule, configured to import the target spectral data into the preset ink optical characteristic database for similarity matching processing, to obtain target spectral similarity corresponding to the target spectral data and each standard sample color block in the preset ink optical characteristic database; a determining submodule, configured to determine the offset color matching data based on the target spectral similarity.

[0069] Optionally, the determining submodule includes a judging unit, configured to judge whether the standard sample color block satisfies the target spectral requirement alone when the target spectral similarity of the standard sample color block and the target spectral data is greater than or equal to a first preset spectral similarity; a first determining unit, configured to determine the base ink type corresponding to the standard sample color block as the offset color matching data if the standard sample color block satisfies the target spectral requirement; a second determining unit, configured to screen a plurality of standard sample color blocks having target spectral similarity greater than or equal to a second preset spectral similarity threshold value from the target spectral data, as the base ink combination, and determine the base ink combination as the offset color matching data if the standard sample color block does not satisfy the target spectral requirement.

[0070] Optionally, the computing module 203 includes: a computing submodule, configured to import the offset color matching data into a preset spectral matching algorithm, to calculate spectral difference data between the offset color matching data and the target spectral feature data; a deployment submodule, configured to perform deployment processing on the offset color matching data based on the spectral difference data, to obtain the offset color matching data.

[0071] Optionally, the production module 204 includes: a color difference calculation module, configured to calculate a color difference value between the offset printing result and the target spot color block; The difference analysis module is configured to, if the color difference value is greater than the preset color difference threshold value, perform difference analysis on the target spectrum data and the measured spectrum data of the offset printing to generate an offset color deviation feature. The updating module is configured to import the offset color deviation feature into the preset offset color conversion algorithm based on spectrum matching of digital-to-offset printing to perform offset iteration processing, and update the offset printing result until the color difference value is less than or equal to the preset color difference threshold value.

[0072] As shown in Figure 3 The present application also provides an electronic device 300, which comprises a processor, and the processor can execute any one of the above-mentioned methods for converting an offset color from digital-to-offset printing based on spectrum matching.

[0073] Specifically, the electronic device 300 comprises a processor 301 and a memory 302, and a computer program for converting an offset color from digital-to-offset printing based on spectrum matching stored in the memory 302 and executable on the processor 301, wherein: The processor 301 executes the computer program of the method for converting an offset color from digital-to-offset printing based on spectrum matching stored in the memory 302 to perform the following steps: Obtain target spectrum feature data; Perform color matching processing on the target spectrum data through a preset ink optical property database to obtain offset printing color matching data, wherein the offset printing color matching data is the type and combination of base inks required for ink matching; Perform matching calculation processing on the target spectrum feature data based on a preset spectrum matching algorithm to obtain offset printing matching ratio data, wherein the offset printing matching ratio data is used to determine the amount ratio of each base ink in the base ink type or the base ink combination; Based on the offset printing color matching data and the offset printing matching ratio data, generate corresponding offset printing results.

[0074] The present application also provides a computer readable storage medium, which stores a computer program, and the computer program is executed by a processor to implement the method for converting an offset color from digital-to-offset printing based on spectrum matching or each process of the method for converting an offset color from digital-to-offset printing based on spectrum matching of an application end, and the same technical effects can be achieved. To avoid repetition, details are not described here.

[0075] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by a computer program instructing relevant hardware, and can be stored in a computer readable storage medium. The program can include the processes of the above-mentioned embodiment methods when executed. The storage medium can be a magnetic disc, an optical disc, a read-only memory (ROM) or a random access memory (RAM).

[0076] The above disclosure is only the preferred embodiments of the present application, and of course cannot limit the scope of the present application. Therefore, equivalent changes made according to the claims of the present application are still within the scope of the present application.

Claims

1. A method for converting spot color production from digital proofing to offset printing based on spectral matching, characterized in that, The method comprises the following steps: acquiring target spectral feature data; performing color matching processing on the target spectral data based on a preset ink optical property database to obtain offset printing color matching data, the offset printing color matching data being required base ink types and base ink combinations for ink matching; performing matching calculation processing on the target spectral feature data based on a preset spectral matching algorithm to obtain offset printing matching ratio data, the offset printing matching ratio data being used to determine the use proportion of each base ink in the base ink types or the base ink combinations; generating corresponding offset printing results based on the offset printing color matching data and the offset printing matching ratio data.

2. The spectral match based digital proof-to-offset spot color transfer method of claim 1, wherein, The acquiring of the target spectral data comprises the following steps: acquiring target spot color data and performing digital proofing processing on the target spot color to generate target spot color blocks; acquiring spectral reflectance data of the target spot color blocks by a spectrophotometer to obtain the target spectral feature data.

3. The spectral matching based digital proof-to-offset spot color transfer method according to claim 1, wherein, Before the step of performing color matching processing on the target spectral data based on the preset ink optical property database to obtain the offset printing color matching data, the method further comprises the following steps: acquiring a set of standard sample color blocks of offset printing inks; performing spectral measurement on each standard sample color block in the set of standard sample color blocks of offset printing inks to obtain corresponding spectral reflectance data of each standard sample color block under a preset printing medium; performing standardization processing on the spectral reflectance data to generate corresponding ink optical property parameters; storing the ink optical property parameters in association with the corresponding standard sample color blocks to form the preset ink optical property database.

4. The spectral match based digital proof-to-offset spot color transfer method of claim 3, wherein, The performing of color matching processing on the target spectral data based on the preset ink optical property database to obtain the offset printing color matching data comprises the following steps: importing the target spectral data into the preset ink optical property database to perform similarity matching processing to obtain target spectral similarities corresponding to each standard sample color block in the preset ink optical property database and the target spectral data; determining the offset printing color matching data based on the target spectral similarities.

5. The spectral match based digital proof-to-offset spot color transfer method according to claim 4, wherein, The determining of the offset printing color matching data based on the target spectral similarities comprises the following steps: when the target spectral similarity between the standard sample color block and the target spectral data is greater than or equal to a first preset spectral similarity, determining whether the standard sample color block satisfies the target spectral requirement alone; if yes, determining the base ink type corresponding to the standard sample color block as the offset printing color matching data; if no, screening a plurality of standard sample color blocks having a target spectral similarity greater than or equal to a second preset spectral similarity threshold value with the target spectral data as the base ink combinations, and determining the base ink combinations as the offset printing color matching data.

6. The spectral match based digital proof-to-offset spot color transfer method according to claim 1, wherein, The performing of matching calculation processing on the target spectral feature data based on the preset spectral matching algorithm to obtain the offset printing matching ratio data comprises the following steps: importing the offset printing color matching data into a preset spectral matching algorithm to calculate spectral difference data between the offset printing color matching data and the target spectral feature data; performing matching processing on the offset printing color matching data based on the spectral difference data to obtain the offset printing matching ratio data.

7. The spectral match based digital proof-to-offset spot color transfer method according to claim 2, wherein, After the step of generating the corresponding offset printing result based on the offset printing color matching data and the offset printing ratio data, the method further includes: Calculate the color difference between the offset printing result and the target spot color block; If the color difference value is greater than the preset color difference threshold, the target spectral data and the offset printing measured spectrum are analyzed to generate spot color deviation characteristics. The spot color deviation characteristics are imported into the preset spot color conversion algorithm based on spectral matching for digital proofing to offset printing for spot color iterative processing, and the offset printing results are updated until the color difference value is less than or equal to the preset color difference threshold.

8. A spectral matching based digital proof-to-offset spot color transfer apparatus, characterized in that, include: The acquisition module is used to acquire the target spectral data; The matching module is used to perform color matching processing on the target spectral data through a preset ink optical property database to obtain offset printing color matching data; The calculation module is used to perform adjustment calculations on the target spectral feature data based on a preset spectral matching algorithm to obtain offset printing ratio data; The production module is used to generate corresponding offset printing results based on the offset printing color matching data and the offset printing ratio data.

9. An electronic device, comprising: include: The memory, the processor, and the computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the spot color conversion method for spectral matching-based digital proofing to offset printing as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the spot color conversion method for digital proofing to offset printing based on spectral matching as described in any one of claims 1 to 7.

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