A method for color consistency control in cross-media printing

Abstract

The present application relates to the technical field of color consistency of cross-media printing, and discloses a color consistency control method for cross-media printing, comprising medium substrate light fingerprint exclusive modeling, source file visual equivalent spectrum mapping, ink dynamic penetration pre-compensation, cross-media co-view anchor closed-loop calibration and environment self-adaptive optimization; the color consistency effect of cross-media printing can be improved through the above control method.

Description

Technical Field

[0001] This invention belongs to the technical field of color consistency in cross-media printing, specifically a method for controlling color consistency in cross-media printing. Background Technology

[0002] The mainstream color management system in the current printing industry has long relied on the traditional technical approach based on ICC profile files. The underlying logic of this approach is to generate a dedicated color profile file for each type of printing medium, and then complete the color separation output for the corresponding medium based on the file. This mode can meet basic color requirements in single-media, small-scale printing scenarios, but once a multi-material production scenario is involved, its technical limitations will be fully amplified. It is impossible to achieve complete color uniformity at the human visual level on media with completely different properties such as paper, metal, and plastic using the same set of design source files.

[0003] For example, in the end-to-end packaging system of high-end brands, the same brand visual design often needs to be implemented on at least 3-4 completely different media, such as paper packaging boxes, metal nameplates, self-adhesive plastic labels, and special paper for shopping bags. According to the traditional ICC scheme, a separate color separation file must be made for each medium. Even if color engineers repeatedly adjust the parameters, the final product often has problems such as the brand red on the paper box being too warm, the same color on the metal nameplate being too cool, and the color saturation on the plastic label being completely mismatched. After receiving the goods, the brand often needs to spend a lot of manpower to screen the products with unqualified color differences one by one.

[0004] Therefore, we propose a method for controlling color consistency in cross-media printing. Summary of the Invention

[0005] The purpose of this invention is to provide a method for controlling color consistency in cross-media printing in order to improve the color consistency effect.

[0006] The technical solution adopted in this invention is as follows:

[0007] A method for controlling color consistency in cross-media printing, wherein the control method is as follows:

[0008] S1: Dedicated modeling of optical fingerprints for media substrates. For all target media to be printed, multi-angle spectral imaging equipment is used to simultaneously collect three-dimensional spectral data of diffuse reflection, specular reflection, and micro-transmission light of the media substrate at three incident angles of 0°, 45°, and 90°. The unique light scattering coefficient, surface microstructure texture features, and ink penetration hysteresis time of the media are extracted. A unique 256-bit optical fingerprint hash code is generated for each medium. All data are stored in the cloud cross-media optical fingerprint feature library, marking the inherent color rendering properties of different media from the physical level, avoiding the defect of traditional single whiteness detection that cannot distinguish similar-looking heterogeneous media.

[0009] S2: Source file visual equivalent spectral mapping imports the RGB source image output from the design end into the color processing module, assigns differentiated visual weights to different color gamuts, improves the color mapping accuracy to 3 times that of the traditional mode for the neutral gray and skin color ranges with the highest sensitivity of the human eye, and appropriately relaxes the mapping redundancy for the high-saturation dark area range with extremely low human eye recognition, directly converts the color of each pixel of the source image into a unified visual equivalent spectral set that is compatible with all target media, rather than the traditional general CMYK values, and completes cross-media visual alignment at the source file level, without the need to generate separate color separation files for each medium;

[0010] S3: Dynamic ink penetration pre-compensation. Before formal printing, three sets of standard ink droplets of different volumes are sprayed in advance on the non-effective edge of the medium to be printed. A high-speed camera captures the dynamic image of the ink diffusion and spreading on the surface of the medium in real time. Based on the optical fingerprint code of the medium, a unique ink penetration curve for this batch of medium is generated. The printing dots are pre-compensated in advance. For mediums with high ink absorption such as Xuan paper, the diffusion margin of the dots at the edge of the light-screen area is reduced in advance. For mediums with low ink absorption such as mirror metal, the dot gaps in the dark area are filled in advance. The difference in ink color development between different media is offset from a physical level.

[0011] S4: Cross-media co-visual anchoring closed-loop calibration constructs a cross-media co-visual anchoring block consisting of 6 neutral gray micro-regions with different gradients and 4 low-saturation brand color micro-regions. The spectral values ​​of all micro-regions are completely aligned in the preset visual equivalent spectrum set. During the printing process, the anchoring block is printed synchronously at the edges of the printing area on all different media. Through a multi-channel spectral acquisition system with cross-station linkage, the color rendering data of the anchoring blocks on all media are synchronized in real time. When the visual color difference ΔE between the anchoring blocks of any two media exceeds 0.8, the system automatically fine-tunes the ink output of the corresponding printing press, and completes the full-link color calibration without stopping the machine.

[0012] S5: Environmental adaptive optimization. A distributed network of temperature, humidity and air pressure sensors is deployed in the printing workshop to collect environmental parameters in real time. Based on the actual color data of each print, the optical fingerprint feature library of the corresponding medium is automatically updated iteratively. When the cumulative printing data of the same medium in different seasons and regions exceeds 10 sets, the system automatically generates an environmental adaptive compensation model for the medium. Subsequent printing of the same medium does not require re-proofing, and the optimal printing parameters are automatically matched directly based on the real-time environmental parameters.

[0013] In a preferred embodiment of the invention, the 256-bit optical fingerprint hash code is generated using the SHA-256 encryption algorithm. The first 64 bits of the code store the basic material identifier of the storage medium, the middle 128 bits store the quantitative characteristic values ​​of the light scattering coefficient, surface microstructure texture features, and ink penetration hysteresis time, and the last 64 bits store the batch traceability verification bits of the storage medium.

[0014] In a preferred embodiment of the invention, the differentiated visual weight allocation is set based on the cone cell response curve of the CIE 2024 human eye visual perception model, with the color mapping sampling step size for the neutral gray range and skin color range set to 0.2ΔE, and the color mapping sampling step size for the high-saturation dark range set to 0.6ΔE.

[0015] In a preferred embodiment of the invention, the three sets of standard ink droplets of different volumes are set to 12 pL, 24 pL and 36 pL respectively, covering the ink jetting volume of the three core color gamut ranges of conventional printing: light halftone, midtone and dark halftone, and the number of sampling points of the generated ink penetration curve is not less than 30.

[0016] In a preferred embodiment of the invention, after the secondary impregnation with the cationic fixing agent, the cross-media common-view anchor block has an overall size of 15mm × 15mm, a size of 2mm × 2mm for each individual micro-area, and a positioning identification mark is provided on the edge of the anchor block. The printing press visual positioning system can complete the position identification of the anchor block within 10ms.

[0017] In a preferred embodiment of the invention, the cross-station linkage multi-channel spectral acquisition system adopts a distributed synchronous acquisition architecture, with the synchronization delay of spectral acquisition data from all printing stations not exceeding 50ms, and can simultaneously support real-time cross-media color calibration for up to 16 different types of printing presses.

[0018] In a preferred embodiment of the invention, the environmental adaptive compensation model is generated by training an LSTM long short-term memory neural network, and the input parameters include four types of variables: real-time temperature and humidity, air pressure, ink viscosity, and medium surface temperature.

[0019] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0020] 1. In this invention, the anchor block specifically selects 6 gradient neutral gray micro-areas and 4 low-saturation brand color micro-areas with the highest sensitivity of the human eye, avoiding the high-saturation dark areas with extremely low human eye recognition. The core anchor point of cross-media color verification is completely placed in the color gamut range where the human eye can most easily perceive color differences. The spectral values ​​of all micro-areas are uniformly aligned in advance in the visual equivalent spectrum set. From the source of verification, the problem of traditional anchor blocks only aligning CMYK values ​​and still having visual discrepancies on different media is avoided, thus improving the color consistency effect of cross-media printing.

[0021] 2. In this invention, a single-source file is adapted to all media by using a unified visual equivalent spectral set, eliminating the need for multi-media color separation file production and the pre-production preparation time for single-batch multi-media printing. At the same time, after accumulating 10 sets of data using an environmental adaptive compensation model, proofing is not required. Furthermore, the environmental adaptive compensation model, constructed using a distributed environmental sensor network and an LSTM long short-term memory neural network, can automatically adjust printing parameters in extreme printing environments such as high humidity during the rainy season and low temperatures in northern winters, without manual intervention, thereby improving production efficiency and reducing production costs.

[0022] 3. In this invention, the inherent color properties of the medium are marked at the physical level using 256-bit SHA-256 optical fingerprint encoding. Even two types of paper with identical whiteness values ​​but different materials can be accurately identified through optical fingerprinting, avoiding the problem of entire batch printing being scrapped due to media misuse. Simultaneously, the batch traceability check bit at the end of the code enables end-to-end color data traceability from raw material entry to finished product exit, providing support for anti-counterfeiting and quality problem localization in printed materials. Attached Figure Description

[0023] Figure 1 This is a flowchart of the control method of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The following will combine Figure 1 A method for controlling color consistency in cross-media printing according to an embodiment of the present invention will be described in detail.

[0026] Example 1:

[0027] Reference Figure 1A method for controlling color consistency in cross-media printing is proposed. The method involves: 1) Dedicated modeling of the optical fingerprint of the substrate; 2) Using a multi-angle spectral imaging device, simultaneously acquiring three-dimensional spectral data of diffuse reflection, specular reflection, and micro-transmission of the substrate at three incident angles (0°, 45°, and 90°) for all target media to be printed; 3) Extracting three core parameters unique to each medium: light scattering coefficient, surface microstructure texture features, and ink penetration hysteresis time; 4) Generating a unique 256-bit optical fingerprint hash code for each medium; 5) Storing all data in a cloud-based cross-media optical fingerprint feature library; 6) Marking the inherent color rendering properties of different media from a physical level, avoiding the limitation of traditional single whiteness detection in distinguishing heterogeneous media with similar appearances; 7) Importing the RGB source image output from the design end into the color processing module to assign differentiated visual characteristics to different color gamuts. The weighting improves color mapping accuracy to three times that of traditional methods for the neutral gray and skin tones, which are most sensitive to the human eye. For the highly saturated dark areas, where the human eye has very low discrimination, the mapping redundancy is appropriately relaxed. Instead of using traditional universal CMYK values, the color of each pixel in the source image is directly converted into a unified visual equivalent spectral set suitable for all target media, achieving cross-media visual alignment at the source file level without needing to generate separate color separation files for each medium. The 256-bit optical fingerprint hash encoding, generated using the SHA-256 encryption algorithm, stores the basic material identifier of the medium in the first 64 bits, the quantified features of light scattering coefficients, surface microstructure texture characteristics, and ink penetration hysteresis time in the middle 128 bits, and the batch traceability verification bits for the medium in the last 64 bits. The differentiated visual weighting allocation is based on CIE... The cone cell response curve settings of the 2024 human visual perception model are as follows: the color mapping sampling step size for the neutral gray and skin color ranges is set to 0.2ΔE, and the color mapping sampling step size for the high-saturation dark area range is set to 0.6ΔE. Specifically, the 256-bit SHA-256 optical fingerprint code is used to mark the inherent color rendering properties of the medium from the physical level. Even two types of paper with completely identical whiteness values ​​but different materials can be accurately identified through optical fingerprinting, avoiding the problem of entire batch printing being scrapped due to media misuse. At the same time, the batch traceability verification bit at the end of the code can realize the traceability of color data from the raw material entering the factory to the finished product leaving the factory, providing support for anti-counterfeiting and quality problem location of printed materials.

[0028] Example 2:

[0029] Reference Figure 1The system employs dynamic ink penetration pre-compensation, where three sets of standard ink droplets of different volumes are pre-sprayed onto the non-effective edges of the printing medium before formal printing. A high-speed camera captures the dynamic images of ink diffusion and spreading on the medium surface in real time. Based on the optical fingerprint code of the medium, a unique ink penetration curve for that batch of medium is generated, pre-compensating the printing dots in advance. For highly absorbent mediums like Xuan paper, the diffusion allowance at the edges of dots in the light halftone areas is reduced in advance; for low-absorbent mirror metal media, dot gaps in the dark areas are filled in advance, physically offsetting the differences in ink color development between different media. The three sets of standard ink droplets, with volumes of 12pL, 24pL, and 36pL respectively, cover the ink spray volume for the three core color gamuts of conventional printing: light halftone, midtone, and dark halftone. The generated ink penetration curve has no fewer than 30 sampling points. Environmental adaptive optimization involves deploying a distributed network of temperature, humidity, and air pressure sensors in the printing workshop to collect environmental parameters in real time. Based on the actual color data of each print run, the system automatically iterates and optimizes. The new optical fingerprint feature library for corresponding media allows the system to automatically generate an environmental adaptive compensation model for the same medium when the accumulated printing data for different seasons and regions exceeds 10 sets. Subsequent printing on the same medium eliminates the need for re-proofing, as the system automatically matches the optimal printing parameters based on real-time environmental parameters. This environmental adaptive compensation model is generated using an LSTM (Long Short-Term Memory) neural network, with input parameters including four types of variables: real-time temperature and humidity, air pressure, ink viscosity, and media surface temperature. Specifically, it achieves single-source file adaptation to all media through a unified visual equivalent spectral set, eliminating the need for multi-media color separation file creation and reducing pre-printing preparation time for single-batch multi-media printing. Furthermore, after accumulating 10 sets of data using the environmental adaptive compensation model, proofing is no longer required. The environmental adaptive compensation model, constructed using a distributed environmental sensor network and an LSTM neural network, can automatically adjust printing parameters in extreme printing environments such as high humidity during the rainy season and low temperatures in northern winters, without manual intervention, thereby improving production efficiency and reducing production costs.

[0030] Example 3:

[0031] Reference Figure 1Cross-media co-visual anchoring closed-loop calibration constructs a cross-media co-visual anchoring block consisting of 6 neutral gray micro-regions with different gradients and 4 low-saturation brand color micro-regions. The spectral values ​​of all micro-regions are completely aligned in a preset visual equivalent spectral set. During printing, this anchoring block is printed synchronously at the edges of the printing areas on all different media. Through a multi-channel spectral acquisition system linked across workstations, the color development data of the anchoring blocks on all media are synchronized in real time. When the visual color difference ΔE between the anchoring blocks of any two media exceeds 0.8, the system automatically fine-tunes the ink output of the corresponding printing press, completing the full-link color calibration without stopping the machine. The cross-media co-visual anchoring block has an overall size of 15mm × 15mm, and the size of a single micro-region is 2mm × 2mm. The anchoring block edge is equipped with positioning identification marks, and the printing press visual positioning system can detect it within 10m. The anchor block position recognition is completed within seconds; the cross-station linkage multi-channel spectral acquisition system adopts a distributed synchronous acquisition architecture, and the synchronization delay of spectral acquisition data of all printing stations does not exceed 50ms. It can simultaneously support real-time cross-media color calibration of up to 16 different types of printing presses; specifically, the anchor block is specially selected to select 6 gradient neutral gray micro-areas and 4 low-saturation brand color micro-areas with the highest sensitivity of human eyes, avoiding the high-saturation dark areas with extremely low human eye recognition. The core anchor point of cross-media color verification is completely placed in the color gamut range where human eyes can most easily perceive color differences. The spectral values ​​of all micro-areas are uniformly aligned in advance in the visual equivalent spectral set. From the source of verification, the problem of traditional anchor blocks only aligning CMYK values ​​and still having visual deviations on different media is avoided, thus improving the color consistency effect of cross-media printing.

[0032] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0033] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling color consistency in cross-media printing, characterized in that, The control method is as follows: S1: Dedicated modeling of optical fingerprints for media substrates. For all target media to be printed, multi-angle spectral imaging equipment is used to simultaneously collect three-dimensional spectral data of diffuse reflection, specular reflection, and micro-transmission light of the media substrate at three incident angles of 0°, 45°, and 90°. The unique light scattering coefficient, surface microstructure texture features, and ink penetration hysteresis time of the media are extracted. A unique 256-bit optical fingerprint hash code is generated for each medium. All data are stored in the cloud cross-media optical fingerprint feature library, marking the inherent color rendering properties of different media from the physical level, avoiding the defect of traditional single whiteness detection that cannot distinguish similar-looking heterogeneous media. S2: Source file visual equivalent spectral mapping imports the RGB source image output from the design end into the color processing module, assigns differentiated visual weights to different color gamuts, improves the color mapping accuracy to 3 times that of the traditional mode for the neutral gray and skin color ranges with the highest sensitivity of the human eye, and appropriately relaxes the mapping redundancy for the high-saturation dark area range with extremely low human eye recognition, directly converts the color of each pixel of the source image into a unified visual equivalent spectral set that is compatible with all target media, rather than the traditional general CMYK values, and completes cross-media visual alignment at the source file level, without the need to generate separate color separation files for each medium; S3: Dynamic ink penetration pre-compensation. Before formal printing, three sets of standard ink droplets of different volumes are sprayed in advance on the non-effective edge of the medium to be printed. A high-speed camera captures the dynamic image of the ink diffusion and spreading on the surface of the medium in real time. Based on the optical fingerprint code of the medium, a unique ink penetration curve for this batch of medium is generated. The printing dots are pre-compensated in advance. For mediums with high ink absorption such as Xuan paper, the diffusion margin of the dots at the edge of the light-screen area is reduced in advance. For mediums with low ink absorption such as mirror metal, the dot gaps in the dark area are filled in advance. The difference in ink color development between different media is offset from a physical level. S4: Cross-media co-visual anchoring closed-loop calibration constructs a cross-media co-visual anchoring block consisting of 6 neutral gray micro-regions with different gradients and 4 low-saturation brand color micro-regions. The spectral values ​​of all micro-regions are completely aligned in the preset visual equivalent spectrum set. During the printing process, the anchoring block is printed synchronously at the edges of the printing area on all different media. Through a multi-channel spectral acquisition system with cross-station linkage, the color rendering data of the anchoring blocks on all media are synchronized in real time. When the visual color difference ΔE between the anchoring blocks of any two media exceeds 0.8, the system automatically fine-tunes the ink output of the corresponding printing press, and completes the full-link color calibration without stopping the machine. S5: Environmental adaptive optimization. A distributed network of temperature, humidity and air pressure sensors is deployed in the printing workshop to collect environmental parameters in real time. Based on the actual color data of each print, the optical fingerprint feature library of the corresponding medium is automatically updated iteratively. When the cumulative printing data of the same medium in different seasons and regions exceeds 10 sets, the system automatically generates an environmental adaptive compensation model for the medium. Subsequent printing of the same medium does not require re-proofing, and the optimal printing parameters are automatically matched directly based on the real-time environmental parameters.

2. The color consistency control method for cross-media printing as described in claim 1, characterized in that: The 256-bit optical fingerprint hash code is generated using the SHA-256 encryption algorithm. The first 64 bits of the code store the basic material identifier of the storage medium, the middle 128 bits store the quantitative feature values ​​of light scattering coefficient, surface microstructure texture features, and ink penetration hysteresis time, and the last 64 bits store the batch traceability verification bits of the storage medium.

3. The color consistency control method for cross-media printing as described in claim 1, characterized in that: The differentiated visual weight allocation is based on the cone cell response curve of the CIE 2024 human eye visual perception model. The color mapping sampling step size for the neutral gray range and skin color range is set to 0.2ΔE, and the color mapping sampling step size for the high-saturation dark range is set to 0.6ΔE.

4. The color consistency control method for cross-media printing as described in claim 1, characterized in that: The three sets of standard ink droplets with different volumes were set to 12pL, 24pL and 36pL respectively, covering the ink jetting volume of the three core color gamut ranges of conventional printing: light halftone, medium tone and dark halftone. The number of sampling points of the generated ink penetration curve was no less than 30.

5. The color consistency control method for cross-media printing as described in claim 1, characterized in that: The cross-media common-view anchor block has an overall size of 15mm×15mm and a single micro-area size of 2mm×2mm. The anchor block edge is provided with positioning identification marks, and the printing press vision positioning system can complete the position identification of the anchor block within 10ms.

6. The color consistency control method for cross-media printing as described in claim 1, characterized in that: The cross-station linkage multi-channel spectral acquisition system adopts a distributed synchronous acquisition architecture, with a synchronization delay of no more than 50ms for spectral acquisition data from all printing stations. It can simultaneously support real-time cross-media color calibration for up to 16 different types of printing presses.

7. The color consistency control method for cross-media printing as described in claim 1, characterized in that: The environmental adaptive compensation model is generated by training an LSTM long short-term memory neural network. The input parameters include four types of variables: real-time temperature and humidity, air pressure, ink viscosity, and medium surface temperature.

Images