A new method of printing a chase

Abstract

This invention discloses a novel method for color matching in printing, relating to the field of printing technology. This method establishes a standard color database, combines high-precision image acquisition and analysis technology, compares the color differences between the printed material and a standard color sample in real time, and generates an ink adjustment scheme based on an intelligent algorithm, achieving rapid and accurate color matching in printing. Compared to traditional color matching methods that rely on manual experience, this invention significantly improves color matching accuracy and efficiency, reduces labor costs, and minimizes ink waste. It is applicable to various packaging printing, book printing, and other scenarios, and has high practicality and promotional value.

Description

Technical Field

[0001] This invention relates to the field of printing technology, and in particular to a novel method for color matching in printing. Background Technology

[0002] Color matching is a crucial step in the printing production process to ensure the consistency of printed colors. Its purpose is to ensure that printed materials from different batches and using different printing equipment maintain consistency with a standard color sample. Traditional color matching relies primarily on the operator's experience, manually observing the differences between the printed material and the standard color sample, and then manually adjusting the ink ratio and printing parameters. This method has the following shortcomings:

[0003] Low precision: Manual observation is easily affected by ambient light and differences in the operator's subjective judgment, making it difficult to accurately identify subtle color deviations, resulting in poor color consistency of printed materials.

[0004] Low efficiency: Manual adjustments require repeated trial printing and comparison, which is tedious and time-consuming, especially in multi-color printing scenarios, which seriously affects production efficiency.

[0005] High cost: Repeated trial printing will result in a large waste of ink and paper, and at the same time, experienced operators are required, resulting in high labor costs.

[0006] Poor stability: Different operators have different experience and judgment standards, which leads to unstable color matching effect of the same printing task at different times and by different operators.

[0007] To address the aforementioned issues, some instrument-based color matching methods have emerged in the existing technology, such as using spectrophotometers to measure color data. However, these methods typically only measure single-point colors and cannot reflect the overall color distribution of the printed material. Furthermore, they lack real-time feedback and intelligent adjustment capabilities, and the color matching effect still needs improvement. Therefore, there is an urgent need for a new printing color matching method that can achieve high precision, high efficiency, and automation. Summary of the Invention

[0008] In view of this, the purpose of this invention is to overcome the shortcomings of low printing color matching accuracy, low efficiency, high cost and poor stability in the prior art, and to provide a new method for printing color matching that achieves accuracy and efficiency in printing color matching through standardized, automated and intelligent technical means.

[0009] This invention provides a novel method for color matching in printing, which aims to achieve the following objectives and benefits: The method includes the following steps:

[0010] Step 1: Standard color data acquisition and storage: Use a high-resolution spectrophotometer to perform full-page color sampling of standard color samples, obtain the CMYK color values ​​and Lab color data of the sampling points, and establish a standard color database;

[0011] Step 2: Color image acquisition of the printed product: Set up a high-precision industrial camera and uniform light source at the paper output end of the printing press to acquire the full-page image of the printed product and record the printing parameters and environmental parameters.

[0012] Step 3: Color Data Comparison and Analysis: Extract the color data of the image to be printed, compare it with the data in the standard color database, calculate the color deviation value ΔE, and determine whether the color of the image to be printed is qualified.

[0013] Step 4: Ink Adjustment Scheme Generation: If the color of the printed product is not up to standard, the intelligent model based on the BP neural network algorithm calculates the amount of ink adjustment based on the color deviation value, printing parameters and environmental parameters, and generates an adjustment scheme.

[0014] Step 5: Ink Adjustment Execution and Closed-Loop Verification: The printing press automatically adjusts the ink parameters according to the adjustment plan, and collects the color data of the product to be printed again for verification until the color is qualified.

[0015] Furthermore, in step one: the sampling point density of the spectrophotometer is not less than 50 points / m², and the standard color database supports retrieval and updating by printing type, batch, and color sample number.

[0016] Furthermore, in step two: the industrial camera has a resolution of no less than 12 million pixels, the light source is a white LED light source with a color temperature of 5000K-6500K, the image acquisition frequency is 30 frames / second, the printing parameters include printing speed, and the environmental parameters include temperature and humidity.

[0017] Furthermore, in step three, the formula for calculating the color deviation value ΔE is: The acceptable standard is ΔE≤1.5;

[0018] Where ΔL is the difference in brightness.

[0019] L represents the brightness or darkness of a color, with a value range of 0 (pure black) to 100 (pure white).

[0020] ΔL = L value of the printout - L value of the standard color sample

[0021] Positive and negative meanings: ΔL>0 → Printed product is too bright; ΔL<0 → Printed product is too dark.

[0022] Δa represents the difference in red and green hues.

[0023] 'a' represents the red-green color axis, with a value range of -128 (pure green) to +127 (pure red).

[0024] Δa = a value of the printout - a value of the standard color sample

[0025] Positive and negative meanings: Δa>0 → Printed product has a reddish tint; Δa<0 → Printed product has a greenish tint.

[0026] Δb represents the difference in yellow and blue tint.

[0027] 'b' represents the yellow-blue color axis, with a value range of -128 (pure blue) to +127 (pure yellow).

[0028] Δb = b-value of printed material - b-value of standard color sample

[0029] Positive and negative meanings: Δb>0 → the printed product will appear yellowish; Δb<0 → the printed product will appear bluish.

[0030] Furthermore, in step four: the intelligent model is generated through training on a large amount of printing sample data. The printing sample data includes the correspondence between color deviation and ink adjustment amount under different ink types, paper types, and printing parameters. The ink adjustment amount includes ink supply amount and ink mixing ratio.

[0031] Furthermore, in step five: the ink adjustment accuracy is 1%, and the closed-loop verification requires repeating steps two and three until the color deviation value ΔE of the entire printed surface is ≤1.5.

[0032] Furthermore, this method is applicable to printing methods such as offset printing, flexographic printing, and gravure printing, and is suitable for printing substrates such as paper, plastic, and metal.

[0033] Furthermore, in step two, after the acquired image data of the product to be printed is transmitted to the computer image processing module, image preprocessing is performed first, and then color data is extracted; the image preprocessing includes noise reduction, white balance correction, and geometric distortion correction using a Gaussian filtering algorithm.

[0034] Furthermore, in step four, the generated adjustment plan includes a specific dot adjustment plan, and the adjustment plan is displayed to the operator in the form of a visual interface, while being automatically transmitted to the ink control module of the printing press.

[0035] This invention provides a novel method for color matching in printing, including a standard color acquisition unit, an online image acquisition unit, an intelligent adjustment decision unit, and an automatic execution and closed-loop verification unit.

[0036] The standard color acquisition unit is used to acquire full-page color data of standard color samples using a high-resolution spectrophotometer and establish a standard color database.

[0037] The online image acquisition unit is located at the paper output end of the printing press and is used to acquire a full-page image of the printed product using a high-precision industrial camera and a uniform light source, and to record printing parameters and environmental parameters; the image processing and analysis unit is used to preprocess the image of the printed product, extract color data and compare it with data in a standard color database, calculate the color deviation value ΔE and determine whether the color is qualified.

[0038] The intelligent adjustment decision unit has a built-in intelligent model based on the BP neural network algorithm, which is used to calculate the amount of ink adjustment based on the color deviation value, printing parameters and environmental parameters, and generate an adjustment plan.

[0039] The automatic execution and closed-loop verification unit is used to transmit the adjustment plan to the printing press and control it to automatically adjust the ink parameters. At the same time, it controls the online image acquisition unit and the image processing and analysis unit to repeatedly execute the acquisition and comparison process until the color is qualified.

[0040] Beneficial effects

[0041] High precision: It uses a high-resolution spectrophotometer and industrial camera to collect colors across the entire print area, and combines the Lab color space to calculate the deviation. It can identify subtle color differences and achieve a color tracking accuracy of ΔE≤1.5, meeting the requirements of high-precision printing.

[0042] High efficiency: It realizes the automation of the process from color acquisition and analysis to ink adjustment, and the color matching time is shortened to 5-10 minutes (traditional manual color matching takes 30-60 minutes), which greatly improves production efficiency;

[0043] Low cost: Reduces ink and paper waste caused by repeated trial printing (waste is reduced by more than 30%), while reducing reliance on highly experienced operators, resulting in a 20%-40% reduction in labor costs;

[0044] High stability: Based on standardized databases and intelligent algorithms, it avoids the influence of subjective human factors, and the color tracking effect is highly consistent across different batches and different devices;

[0045] Wide applicability: It can be adapted to various printing methods such as offset printing, flexographic printing, and gravure printing, and is suitable for different printing substrates such as paper, plastic, and metal, with a wide range of applications. Attached Figure Description

[0046] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings of the embodiments will be briefly described below.

[0047] The accompanying drawings described below are only related to some embodiments of the invention and are not intended to limit the invention.

[0048] In the attached diagram:

[0049] Figure 1 This is a schematic diagram of the overall process of a novel printing color matching method according to an embodiment of the present invention. Detailed Implementation

[0050] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0051] Example 1: Please refer to Figure 1 As shown:

[0052] This invention provides a novel method for color matching in printing, comprising the following steps:

[0053] Step 1: Standard color data acquisition and storage: Use a high-resolution spectrophotometer to perform full-page color sampling of standard color samples, obtain the CMYK color values ​​and Lab color data of the sampling points, and establish a standard color database;

[0054] Step 2: Color image acquisition of the printed product: Set up a high-precision industrial camera and uniform light source at the paper output end of the printing press to acquire the full-page image of the printed product and record the printing parameters and environmental parameters.

[0055] Step 3: Color Data Comparison and Analysis: Extract the color data of the image to be printed, compare it with the data in the standard color database, calculate the color deviation value ΔE, and determine whether the color of the image to be printed is qualified.

[0056] Step 4: Ink Adjustment Scheme Generation: If the color of the printed product is not up to standard, the intelligent model based on the BP neural network algorithm calculates the amount of ink adjustment based on the color deviation value, printing parameters and environmental parameters, and generates an adjustment scheme.

[0057] Step 5: Ink Adjustment Execution and Closed-Loop Verification: The printing press automatically adjusts the ink parameters according to the adjustment plan, and collects the color data of the product to be printed again for verification until the color is qualified.

[0058] In step one, the sampling point density of the spectrophotometer is not less than 50 points / m², and the standard color database supports retrieval and updating by printing type, batch, and color sample number.

[0059] In step two, the industrial camera has a resolution of no less than 12 million pixels, the light source is a white LED light source with a color temperature of 5000K-6500K, the image acquisition frequency is 30 frames / second, the printing parameters include printing speed, and the environmental parameters include temperature and humidity.

[0060] In step three, the formula for calculating the color deviation value ΔE is: The acceptable standard is ΔE≤1.5;

[0061] Where ΔL is the difference in brightness.

[0062] L represents the brightness or darkness of a color, with a value range of 0 (pure black) to 100 (pure white).

[0063] ΔL = L value of the printout - L value of the standard color sample

[0064] Positive and negative meanings: ΔL>0 → Printed product is too bright; ΔL<0 → Printed product is too dark.

[0065] Δa represents the difference in red and green hues.

[0066] 'a' represents the red-green color axis, with a value range of -128 (pure green) to +127 (pure red).

[0067] Δa = a value of the printout - a value of the standard color sample

[0068] Positive and negative meanings: Δa>0 → Printed product has a reddish tint; Δa<0 → Printed product has a greenish tint.

[0069] Δb represents the difference in yellow and blue tint.

[0070] 'b' represents the yellow-blue color axis, with a value range of -128 (pure blue) to +127 (pure yellow).

[0071] Δb = b-value of printed material - b-value of standard color sample

[0072] Positive and negative meanings: Δb>0 → the printed product will appear yellowish; Δb<0 → the printed product will appear bluish.

[0073] In step four, the intelligent model is generated through training on a large amount of printing sample data. The printing sample data includes the correspondence between color deviation and ink adjustment amount under different ink types, paper types, and printing parameters. The ink adjustment amount includes ink supply amount and ink mixing ratio.

[0074] In step five, the ink adjustment accuracy is 1%, and the closed-loop verification requires repeating steps two and three until the color deviation value ΔE of the entire printed surface is ≤1.5.

[0075] This method is applicable to printing methods such as offset printing, flexographic printing, and gravure printing, and is suitable for printing substrates such as paper, plastic, and metal.

[0076] In step two, after the acquired image data of the product to be printed is transmitted to the computer image processing module, image preprocessing is performed first, and then color data is extracted. The image preprocessing includes noise reduction, white balance correction, and geometric distortion correction using a Gaussian filtering algorithm.

[0077] In step four, the generated adjustment plan includes a specific dot adjustment plan, which is displayed to the operator in a visual interface and automatically transmitted to the ink control module of the printing press.

[0078] This invention provides a system for a novel method of color matching in printing, comprising:

[0079] Standard color acquisition unit, online image acquisition unit, intelligent adjustment decision unit, and automatic execution and closed-loop verification unit;

[0080] The standard color acquisition unit is used to acquire full-page color data of standard color samples using a high-resolution spectrophotometer and establish a standard color database.

[0081] The online image acquisition unit is located at the paper output end of the printing press and is used to acquire a full-page image of the printed product using a high-precision industrial camera and a uniform light source, and to record printing parameters and environmental parameters; the image processing and analysis unit is used to preprocess the image of the printed product, extract color data and compare it with data in a standard color database, calculate the color deviation value ΔE and determine whether the color is qualified.

[0082] The intelligent adjustment decision unit has a built-in intelligent model based on the BP neural network algorithm, which is used to calculate the amount of ink adjustment based on the color deviation value, printing parameters and environmental parameters, and generate an adjustment plan.

[0083] The automatic execution and closed-loop verification unit is used to transmit the adjustment plan to the printing press and control it to automatically adjust the ink parameters. At the same time, it controls the online image acquisition unit and the image processing and analysis unit to repeatedly execute the acquisition and comparison process until the color is qualified.

[0084] Experimental data:

[0085] (1) Standard color data acquisition: Select standard color samples of packaging boxes (material is 250g white cardboard), use X-Rite eXact spectrophotometer to sample the entire surface of the standard color samples, the sampling point density is 80 points / ㎡, obtain the color data of Lab value (e.g.: L=68, a=-2, b=28) corresponding to the CMYK value (e.g. C: 35%, M: 20%, Y: 15%, K: 5%) of each sampling point, and establish a standard color database.

[0086] (2) Color acquisition of the printed matter: A Hikvision 12-megapixel industrial camera with a 5500K white LED light source is set at the paper output end of the Heidelberg SM74 offset printing press. When the printed matter (250g white cardboard of the same batch) is output, the camera acquires the full-page image at a frequency of 30 frames / second, while recording the printing speed of 12,000 sheets / hour, the ambient temperature of 25℃, and the humidity of 50%.

[0087] (3) Color contrast analysis: The image processing module extracts the color data of the sampling points of the product to be printed, obtains the Lab values ​​(e.g., L1=67, a1=-3, b1=26) corresponding to the CMYK values ​​(e.g., C: 35%, M: 20%, Y: 15%, K: 5%) of the corresponding sampling points, calculates the color deviation value ΔE=2.4 (>1.5), and determines that ink adjustment is required.

[0088] (4) Adjustment scheme generation: The intelligent algorithm model calculates the ink adjustment amount based on the color deviation data and printing parameters: the C ink supply increases by 1%, the Y ink supply decreases by 3%, and the MK ink supply remains unchanged. The adjustment scheme is generated and transmitted to the printing press ink control module.

[0089] (5) Adjustment and verification: After the printing press automatically adjusts the ink supply, the camera continues to collect images of the product to be printed and re-analyzes the color data. At this time, the ΔE of the sampling point is 1.2 (≤1.5), and the color is judged to be qualified, and the normal printing process begins.

[0090] The color matching process took 8 minutes, which is 82% more efficient than traditional manual color matching (45 minutes), reduces ink waste by 35%, and ensures that the color consistency of the printed products meets the customer's requirements.

Claims

1. A new method of printing a chase, characterized in that, Includes the following steps: Step 1: Standard color data acquisition and storage: Use a high-resolution spectrophotometer to perform full-page color sampling of standard color samples, obtain the CMYK color values ​​and Lab color data of the sampling points, and establish a standard color database; Step 2: Color image acquisition of the printed product: Set up a high-precision industrial camera and uniform light source at the paper output end of the printing press to acquire the full-page image of the printed product and record the printing parameters and environmental parameters. Step 3: Color Data Comparison and Analysis: Extract the color data of the image to be printed, compare it with the data in the standard color database, calculate the color deviation value ΔE, and determine whether the color of the image to be printed is qualified. Step 4: Ink Adjustment Scheme Generation: If the color of the printed product is not up to standard, the intelligent model based on the BP neural network algorithm calculates the amount of ink adjustment based on the color deviation value, printing parameters and environmental parameters, and generates an adjustment scheme. Step 5: Ink Adjustment Execution and Closed-Loop Verification: The printing press automatically adjusts the ink parameters according to the adjustment plan, and collects the color data of the product to be printed again for verification until the color is qualified.

2. A new method of print registration according to claim 1, characterized in that: In step one: the sampling point density of the spectrophotometer is not less than 50 points / m², and the standard color database supports retrieval and updating by printing type, batch, and color sample number.

3. A new method of print registration according to claim 1, characterized in that: In step two: the industrial camera has a resolution of no less than 12 million pixels, the light source is a white LED light source with a color temperature of 5000K-6500K, the image acquisition frequency is 30 frames / second, the printing parameters include printing speed, and the environmental parameters include temperature and humidity.

4. A novel method for color matching in printing according to claim 1, characterized in that: In the third step, the color deviation value ΔE is calculated according to the following formula: The qualified standard is ΔE≤1.

5. Where ΔL is the difference in brightness. L represents the brightness or darkness of a color, with a value range of 0 (pure black) to 100 (pure white). ΔL = L value of the printout - L value of the standard color sample Positive and negative meanings: ΔL>0 → Printed product is too bright; ΔL<0 → Printed product is too dark. Δa represents the difference in red and green hues. 'a' represents the red-green color axis, with a value range of -128 (pure green) to +127 (pure red). Δa = a value of the printout - a value of the standard color sample Positive and negative meanings: Δa>0 → Printed product has a reddish tint; Δa<0 → Printed product has a greenish tint. Δb represents the difference in yellow and blue tint. 'b' represents the yellow-blue color axis, with a value range of -128 (pure blue) to +127 (pure yellow). Δb = b-value of printed material - b-value of standard color sample Positive and negative meanings: Δb>0 → the printed product will appear yellowish; Δb<0 → the printed product will appear bluish.

5. A novel method for color matching in printing according to claim 1, characterized in that: In step four: the intelligent model is generated through training on a large amount of printing sample data. The printing sample data includes the correspondence between color deviation and ink adjustment amount under different ink types, paper types, and printing parameters. The ink adjustment amount includes ink supply amount and ink mixing ratio.

6. A novel method for printing color matching according to claim 1, characterized in that: In step five: the ink adjustment accuracy is 1%, and the closed-loop verification requires repeating steps two and three until the color deviation value ΔE of the entire printed surface is ≤1.

5.

7. The novel method for printing color matching according to any one of claims 1-6, characterized in that: This method is applicable to printing methods such as offset printing, flexographic printing, and gravure printing, and is suitable for printing substrates such as paper, plastic, and metal.

8. A novel method for printing color matching according to claim 3, characterized in that: In step two, after the acquired image data of the product to be printed is transmitted to the computer image processing module, image preprocessing is performed first, and then color data is extracted. The image preprocessing includes noise reduction, white balance correction, and geometric distortion correction using a Gaussian filtering algorithm.

9. A novel method for color matching in printing according to claim 5, characterized in that: In step four, the generated adjustment plan includes a specific dot adjustment plan, which is displayed to the operator in a visual interface and automatically transmitted to the ink control module of the printing press.

10. A system for a novel method of color matching in printing, characterized in that: include: Standard color acquisition unit, online image acquisition unit, intelligent adjustment decision unit, and automatic execution and closed-loop verification unit; The standard color acquisition unit is used to acquire full-page color data of standard color samples using a high-resolution spectrophotometer and establish a standard color database. The online image acquisition unit is located at the paper output end of the printing press and is used to acquire a full-page image of the printed product using a high-precision industrial camera and a uniform light source, and to record printing parameters and environmental parameters; the image processing and analysis unit is used to preprocess the image of the printed product, extract color data and compare it with data in a standard color database, calculate the color deviation value ΔE and determine whether the color is qualified. The intelligent adjustment decision unit has a built-in intelligent model based on the BP neural network algorithm, which is used to calculate the amount of ink adjustment based on the color deviation value, printing parameters and environmental parameters, and generate an adjustment plan. The automatic execution and closed-loop verification unit is used to transmit the adjustment plan to the printing press and control it to automatically adjust the ink parameters. At the same time, it controls the online image acquisition unit and the image processing and analysis unit to repeatedly execute the acquisition and comparison process until the color is qualified.

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