Correlation of homogeneity using a spectroscopic camera

Abstract

This achieves uniform density in the solid color areas of an image printed by multiple print heads equipped with multiple nozzles. [Solution] The printing system receives a print job that includes solid color areas associated with uniform color values. The system determines an array that maps the uniform color values ​​to density values ​​measured by a spectrophotometer. Using this array, a template is obtained from the printing system's raster image processor, and the density values ​​are mapped to intensity values ​​for the printer nozzles. This template is used to determine the intensity value for each nozzle based on the density of the corresponding uniform color values. The printing system prints the image according to the determined intensity values, achieving a uniform color distribution throughout the printed image.

Description

Technical Field

[0001] The embodiments described herein generally relate to printing systems. More specifically, it relates to a method for achieving a uniform density in the solid areas of an image printed by a plurality of print heads having a plurality of nozzles.

Background Art

[0002] Inkjet printing technology involves accurately ejecting ink droplets from nozzles onto a printing medium. Print heads are typically arranged linearly or staggered to cover the entire width of the printing area. Each print head comprises a large number of nozzles, the number of which ranges from several tens to several thousands depending on the printer design and application. Solid area printing, which is a process of printing a wide continuous area of color or tone without gaps or interruptions, is a particularly difficult problem in inkjet systems. Density variations in solid areas can be caused by manufacturing variations or other factors, all of which can produce color differences and require measurement and correction.

Summary of the Invention

[0003] This specification describes systems and approaches for achieving uniform density in solid areas of an image printed by multiple printheads having multiple nozzles. In some embodiments, a printing system receives a print job containing a set of solid color areas of an image to be printed by a set of printer nozzles. The set of solid color areas is associated with a set of uniform color values. An array is determined, which includes one or more mappings of the set of uniform color values ​​to a set of density values ​​measured using a spectrophotometer. Using the determined array, the printing system obtains a template from the printing system's raster image processor. The template maps the density values ​​of the set of uniform color values ​​to a set of intensity values ​​for the printer nozzles. The obtained template is used to determine the intensity value of each printer nozzle based on the density value of the uniform color values ​​corresponding to each solid area. As a result, the printing system prints the image according to the determined intensity values ​​of the set of printer nozzles.

[0004] The exemplary embodiments of this specification include a first printing system that determines an array by using a second printing system that prints a set of targets, each defined by a color value. The second system measures these targets using embedded sensors and a spectrophotometer to obtain spectral measurements that are converted into density values. This array is generated by aggregating the color values ​​and their corresponding density values. This method includes smoothing and interpolating these values ​​to reduce noise and match them to predetermined values, resulting in a three-dimensional lookup table. Stored in the raster image processor of the printing system, this array includes multiple bands, each containing the density of a color channel (red, green, blue). Based on these bands, the raster image processor evaluates the intensity value of each printer nozzle using this array, which is encoded in binary format.

[0005] These aspects, features, and implementations can be expressed as methods, apparatus, systems, components, program products, means or steps for performing functions, and in other ways. These aspects, features, and embodiments will become apparent from the following description, including the claims. [Brief explanation of the drawing]

[0006] [Figure 1] This block diagram shows a perspective view of a printing system according to one or more embodiments. [Figure 2] This block diagram shows a side view of a printing system including a printer head and a light source, according to one or more embodiments. [Figure 3] This figure shows an example of an environment for printing solid areas using one or more embodiments. [Figure 4] This figure shows an example of a color template for detecting solid areas, according to one or more embodiments. [Figure 5] This figure shows an example of a lookup table according to one or more embodiments. [Figure 6] This flowchart illustrates a process for achieving uniform concentration in a solid region using one or more embodiments. [Figure 7] This is a block diagram showing an exemplary computer system according to one or more embodiments. [Modes for carrying out the invention]

[0007] The following description includes many specific details for the sake of clarity and to ensure a complete understanding of this embodiment. However, it will be clear that this embodiment can be implemented without these specific details.

[0008] This specification presents systems, methods, and apparatus for achieving uniform density in solid areas of an image printed by multiple printheads equipped with multiple nozzles. Conventional methods for correcting color misalignment in printing systems typically involve integrating a spectrophotometer into the printer to measure solid patches with different ink coverages and then calculating the required ink adjustment. While this method provides accurate spectral measurements, spectrophotometers are expensive, making their integration into printers costly and only feasible in multi-pass printers where the sensor can scan the entire print width. Conventional methods can also be used in single-pass printers, employing a series of sensors (scanners or cameras) that approximate color density using red, blue, and green (RGB) values. However, this method relies on non-spectral values, resulting in low accuracy and only allowing for approximate estimation of color density. Therefore, the effectiveness of conventional methods is sometimes limited.

[0009] Embodiments disclosed herein provide a method for receiving print jobs that include solid color areas associated with uniform color values. The array is determined so as to map the uniform color values ​​to density values ​​measured using a spectrophotometer. A template mapping the density values ​​to intensity values ​​for printer nozzles is obtained from a raster image processor. This template is used to determine the intensity value for each nozzle based on the density of the corresponding uniform color values, and the printing system is then able to print the image accordingly.

[0010] The advantages and effects of the method for achieving uniform density in solid image areas using the embodiments described herein include improved color accuracy and consistency, reduced printing defects such as banding and color misalignment, and improved overall print quality. By obtaining more accurate spectral measurements using a spectrophotometer and directly converting these measurements to density values, this method ensures that the intensity of each nozzle is accurately calibrated to the corresponding color value, eliminating the need to physically incorporate a spectrophotometer into the printing system that prints the image. Storing accurate spectral measurements in a three-dimensional lookup table (e.g., array) allows the printing system to print a uniform color distribution across the entire printed image without referencing spectral measurements and without needing to incorporate a spectrophotometer into the printing system itself, or relying on less accurate estimations. This provides greater flexibility in the selection of printing hardware and configuration. Printing system

[0011] Figure 1 is a schematic diagram of a printing system 100 according to one or more embodiments. The printing system 100 comprises a printer head 106, at least one light source 112, and a transfer belt 102. Embodiments may include other components (e.g., a dryer). For example, the light source 112 is present in some embodiments but not in others. As another example, a dryer is incorporated if the image 110 is not to be transferred to the garment quickly. In some examples, the printing system 100 in Figure 1 comprises a transfer belt 102, but other means for transporting and / or holding the substrate or transfer material 104, such as a rotating platform or a fixed bed, may also be used.

[0012] The printer head 106 is configured to eject ink onto the transfer material 104 in the form of an image 110. The transfer material 104, also referred to herein as a molding material, is flexible, making it possible to transfer the image 110 to a substrate with a complex shape. For example, the transfer material 104 may be a rubber molding material, a thermoformable material, etc. In some embodiments, the printer head 106 is an inkjet printer head that, for example, uses a piezo nozzle to spray ink onto the transfer material 104. Thermal printer heads are generally not used to avoid premature sublimation of the ink. In some embodiments, the ink is a solid energy-curing ink, e.g., a UV-curing ink. However, other inks, such as water-based energy-curing inks or solvent-based energy-curing inks, are also used. According to various embodiments, the ink is ejected in various forms, such as ink droplets and colored polyester ribbons.

[0013] In some embodiments, one or more light sources 112 cure some or all of the ink ejected onto the transfer material 104 by irradiating it with UV radiation. In some examples, the light sources 112 are any combination of UV fluorescent lamps, UV light-emitting diodes (LEDs), low-pressure mercury (Hg) lamps, or excimer lamps and / or lasers. Various combinations of these light sources can be used. In some examples, the printing system 100 includes a low-pressure mercury lamp and a UV LED. The light sources 112 may be configured to emit a specific type of UV radiation.

[0014] The printer head 106 and the light source 112 are shown directly adjacent to each other, that is, next to each other without any components intervening between them. However, in other embodiments, additional components may also be present to assist with printing, curing, etc. In some examples, multiple different light sources 112 are positioned behind the printer head 106. Figure 1 shows one possible order in which the components are arranged to print the image 110 onto the transfer material 104. Other embodiments are also conceivable in which further components are arranged before, between, or after the illustrated components.

[0015] In some embodiments, one or more of the aforementioned components are housed in one or more stations. For example, the printer head 106 is housed in the printing station 108, the light source 112 is housed in the irradiation station 114, and so on. The stations not only protect the components from damage, but also, in some examples, offer other advantages. For example, the curing irradiation station 114 limits the portion of the transfer material 104 and the image 110 that is exposed during the curing process. The stations may be permanently mounted on the track or chassis of the printing system 100. The transfer material 104 moves relative to the printer head 106, light source 112, etc., so that ink is deposited on the transfer material 104.

[0016] In various embodiments, some or all of the components are controlled by a computer system 116. In some examples, the computer system 116 allows the user to input print instructions and information, change print settings (e.g., by changing the curing settings), modify the print process, and so on.

[0017] Figure 2 is a block diagram showing a side view of a printing system 200 including a printer head 202 and a light source 204, according to one or more embodiments. In some examples, the printer head 202 includes individual ink / color drums (e.g., cyan, magenta, yellow, and black (CMYK)) or a colored polyester ribbon deposited on the surface of a transfer material 206. Path A represents the media feeding direction, i.e., the direction in which the transfer material 206 moves during the printing process. Path D represents the distance between the printer head 202 and the surface of the transfer material 206.

[0018] In some embodiments, the light source 204 cures some or all of the ink 208 deposited on the transfer material 206 by the printer head 202. In some examples, the light source 204 is configured to emit wavelengths of UV electromagnetic radiation subtype V (UVV), subtype A (UVA), subtype B (UVB), subtype C (UVC), or any combination thereof. Generally, UVV wavelengths are measured between 395 nanometers (nm) and 445 nm, UVA wavelengths between 315 nm and 395 nm, UVB wavelengths between 280 nm and 315 nm, and UVC wavelengths between 100 nm and 280 nm. However, those skilled in the art will understand that these ranges are somewhat adjustable. For example, in some embodiments, a wavelength of 285 nm is characterized as UVC.

[0019] In some examples, the light source 204 is, for example, a fluorescent lamp, a light-emitting diode (LED), a low-pressure mercury lamp, or an excimer lamp / laser. In some embodiments, a combination of different light sources may also be used. Generally, the light source 204 is selected so that the curing temperature does not exceed the temperature at which the ink 208 begins to sublimate. For example, the light source may be a UV LED lamp, which has low heat generation and can handle a wider variety of inks. UV LED lamps have the advantages of low power consumption, long lifespan, and more predictable power output.

[0020] Alternatively or in addition, other curing processes such as epoxy (resin) chemistry, flash curing, electron beam technology are also used. Those skilled in the art will understand that many different curing processes can be employed that utilize specific time frames, strengths, speeds, etc. In some embodiments, the strength increases or decreases linearly or non-linearly (e.g., exponentially or logarithmically). In some embodiments, the light intensity is adjusted using a variable resistor or, alternatively, in the case of an LED light source, by applying a pulse-width-modulated (PWM) signal to the diode. In some examples, the light is modulated using amplitude modulation, polarization modulation, frequency modulation (e.g., wavelength-division multiplexing (WDM)), phase modulation (e.g., angular phase control), time modulation, etc.

[0021] FIG. 3 is a diagram showing an example of an environment 300 for printing a solid area according to one or more embodiments. The components of the environment 300 shown in FIG. 3 include a target pattern 302, a spectrophotometer 304, an RGB sensor 306, a spectral measurement 308, an intensity value 310, an RGB measurement 312, a look-up table 314, a uniformity band 316, an RGB sensor 318, an intensity curve 320, an image before correction 322, a raster image processor 324, and an image after correction 326. Other components of the environment 300 include the components of the computer system 7 shown and described in more detail in FIG. 7, and / or the components of the printing system 100 shown and described in more detail in FIG. 1. Similarly, other embodiments include different and / or additional components or are connected in different ways.

[0022] The system (e.g., printing system 100) prints a target pattern 302. An example of the printing system is described in more detail with reference to the printing system 100 in FIG. 1. The target pattern 302 is a predetermined arrangement of colors or shapes. The target pattern 302 can include a series of color patches or gradations with uniform color values that cover the entire spectrum of colors that the printing system can generate. The target pattern 302 is used as a reference for measuring and calibrating the color output of the printing system. Using the measurements obtained from the target pattern 302 (e.g., by spectrophotometer 304), the printing system can identify discrepancies such as banding and color misregistration in the color density between the target pattern and the uncorrected image 322, and perform the adjustments (e.g., calibration of the printer nozzle intensity) necessary to ensure uniformity.

[0023] The spectrophotometer 304 is a device used to measure the intensity of light at different wavelengths. In the context of the printing system, the spectrophotometer 304 is used to measure the color values of the printed target pattern 302. The spectrophotometer 304 provides spectral measurements 308 by analyzing the light reflected or transmitted by the printed color of the target pattern 302. The spectral measurements 308 are data obtained from the spectrophotometer and enable the printing system to quantify the accurate color output with respect to the spectral data. The spectral measurements 308 can include the intensity of light absorbed or reflected by the colors printed at various wavelengths. The data within the spectral measurements 308 provides a profile of the color output for a specific color within the target pattern 302 (including information regarding the hue, saturation, and brightness of each color). By using the spectrophotometer 304 to obtain the spectral measurements 308, the printing system can identify the specific wavelengths at which color misregistration occurs in the image 322 before correction. The spectral measurements 308 can be converted into intensity values 310. The intensity values 310 represent the strength or brightness of a specific color in the target pattern 302.

[0024] The RGB sensor 306 is a device that detects the levels of red, green, and blue light in a printed target pattern. The RGB sensor 306 obtains RGB measurements 312 (e.g., RGB values, color values) of the target pattern 302. These values ​​are used to determine the overall color accuracy and uniformity of the uncorrected image 322. The RGB sensor 306 works by filtering the incident light into its red, green, and blue components (e.g., RGB measurements 312) and then measuring each component. The RGB measurements 312 represent colors in a digital system by combining red, green, and blue light. Each of these three colors can have an intensity value between 0 and 255. A wide spectrum of colors can be created by mixing the three colors in different ratios. The format for representing RGB color values ​​can be RGB(R, G, B), where RGB are integers between 0 and 255. For example, pure red is represented as RGB(255, 0, 0), pure green as RGB(0, 255, 0), pure blue as RGB(0, 0, 255), black as RGB(0, 0, 0), and white as RGB(255, 255, 255). In some embodiments, an RGB sensor 306 is placed in the optical path of the printing system to continuously monitor the color output of the target pattern 302 during the printing process. The RGB measurement 312 provides a quantitative evaluation of the color output.

[0025] The lookup table 314 is a data structure generated from intensity values ​​310 and RGB measurement values ​​312, which maps the uniform color values ​​of the target pattern 302 to corresponding density values. The lookup table 314 is used by the printing system to determine the appropriate intensity values ​​for the printer nozzles. The printing system uses the intensity values ​​310 and RGB measurement values ​​312 to create a mapping between input color values ​​and desired output density values. This mapping allows the system to accurately reproduce colors by adjusting the intensity of the printer nozzles based on the measured density values. The method for generating the lookup table 314 is described in more detail with reference to Figures 5 and 6.

[0026] A uniformity band 316 refers to a specific horizontal section of a solid color area, which can be a large area with a unique color value printed by one or more printer nozzles. For example, multiple uniformity bands 316 can be placed at different densities and associated with a specific color. Other examples of uniformity bands are illustrated with reference to Figure 4. The method for acquiring the uniformity band 316 is illustrated in more detail with reference to Figures 4 and 6. The RGB sensor 318 is the same as or similar to the RGB sensor 306 and is used to capture RGB measurements of the uniformity band 316. The RGB sensor 318 can be placed in a different location from the RGB sensor 306 to monitor the color of the uniformity band 316. In some embodiments, the RGB sensor 318 is placed in a separate printing system from the RGB sensor 306.

[0027] The intensity curve 320 graphically represents the relationship between the color density value and the corresponding intensity value when each printer nozzle prints a density band. The number of intensity curves 320 is the same as the number of uniformity bands 316. The intensity curve 320 graphically shows the correlation between the RGB measurement value of the printer nozzle and the change in intensity at a specific density. The method for generating the intensity curve 320 is explained in more detail with reference to Figures 4 and 6.

[0028] Image 322 before correction is the first print image before color calibration or adjustment is performed. Image 322 before correction serves as a reference for identifying variations in color density and determining the necessary corrections. Image 322 before correction serves as a reference for evaluating the color accuracy and uniformity of the print output. By comparing the image before correction with the target pattern, the system can identify areas where the color output deviates from the desired value and correct the deviation by adjusting the intensity of one or more printer nozzles.

[0029] The raster image processor 324 is a component of the printing system that converts digital images into a format suitable for printing. The raster image processor 324 processes the image data and applies the necessary color corrections based on the intensity curve 320. The raster image processor 324 can convert the uncorrected image 322 into a raster format that can be printed by the printer nozzle. After the raster image processor 324 corrects the uncorrected image 322 using the intensity curve 320, the corrected image 326 is printed. The corrected image 326 is the final printed image after all color adjustments and calibrations have been applied by the raster image processor 324. The corrected image 326 represents the desired output with uniform color density and accurate color reproduction. By generating the intensity curve 320 using spectral measurements 308 in the lookup table 314, the system can ensure that the corrected image 326 has a consistent color output without banding or other artifacts.

[0030] Figure 4 shows an example of a color template 400 for detecting solid areas according to one or more embodiments. The components of the color template 400 shown in Figure 4 include uniformity bands 402, 404, 406, 408 and intensity curves 410. In some embodiments, uniformity bands 402, 404, 406, 408 can be replaced with uniformity band 316. Other components of the color template 400 include components of a computer system 700, which will be described in more detail with reference to Figure 7. Similarly, other embodiments may include different components and / or additional components, or be connected in different ways.

[0031] In the color template 400 shown in Figure 4, the system generates an intensity curve 410 that reflects any variation in the color output of uniformity bands 402, 404, 406, 408 from one or more printer nozzles of the system. These variations include, for example, manufacturing tolerances (e.g., This can be caused by factors such as droplets ejected from some nozzles exhibiting higher intensity than those from others. Uniformity bands 402, 404, 406, and 408 refer to specific horizontal sections of uniform color density. Uniformity bands 402, 404, 406, and 408 can be positioned at various densities (e.g., 100%, 95%, 90%, ...10%, 5%) for each color channel. Each of the uniformity bands 402, 404, 406, and 408 can be associated with a specific color. For example, in Figure 4, uniformity band 402 is associated with various densities of black, uniformity band 404 with various densities of blue, uniformity band 406 with various densities of red, and uniformity band 408 with various densities of yellow. These color densities can be set to predefined reference values ​​(e.g., in 10% increments). In some embodiments, these reference values ​​can be adjusted by the user (e.g., changed from 10% increments to 5% increments).

[0032] The color template 400 can be printed and scanned using an RGB sensor (e.g., the RGB sensor 318 in Figure 3). The vertical density changes in each band (depending on each printer nozzle printing the corresponding band) are evaluated, and a unique value (a floating-point number between 0 and 1) is assigned to each printer nozzle. This generates an intensity curve 410 with the same number of points as the number of printer nozzles in the corresponding band. This intensity curve 410 graphically represents the relationship between the color density value and the corresponding intensity value.

[0033] For example, in Figure 4, intensity curve 410 is characterized by an average density value of 0.7188 and a standard deviation of 0.0619. These represent the average color density and its variability, respectively. The average density value of 0.7188 represents the average color density obtained at different intensity levels. This is calculated by summing all density values ​​and dividing by the number of values. This value represents the typical color density produced by the printer overall. The standard deviation of 0.0619 measures the degree of variability or dispersion of the average color of the density values. A smaller standard deviation indicates that the density values ​​are clustered more tightly around the mean, while a larger standard deviation indicates that the values ​​are more widely distributed. The observed minimum and maximum density values ​​are 0.5150 and 0.8136, respectively. The minimum and maximum density values ​​indicate the range of color densities obtained at different intensity levels. The minimum density value of 0.5150 is the lowest color density observed in the dataset. This value indicates the smallest amount of ink or toner adhering to the paper at a particular intensity level. The maximum density value of 0.8136 is the highest color density observed in the dataset. This value indicates the highest amount of ink or toner adhering to the paper at a given intensity level. The system can use the intensity curve 410 to identify the required intensity setting for each printer nozzle and compensate for the printer nozzle intensity in subsequent print jobs, thereby ensuring consistent color output in the solid color areas of the printed image.

[0034] Figure 5 shows an example of a lookup table 500 according to one or more embodiments. The components of the lookup table 500 shown in Figure 5 include color channels 502, 504, 506, color values ​​508, 510, 512, and intensity value 514. Other components of the lookup table 500 include components of a computer system 700, which will be described in more detail with reference to Figure 7. Similarly, other embodiments may include different components and / or additional components, or be connected in different ways.

[0035] Color channels 502, 504, and 506 represent the individual color components that make up the final printed image. For example, color channels 502, 504, and 506 can represent red, green, and blue. Each color channel is responsible for a specific wavelength range in the visible spectrum, and the combination of these channels generates the entire color range in the printed image. Color values ​​508, 510, and 512 represent specific color measurements obtained from the printed image defined by color channels 502, 504, and 506. Further examples of color channels 502, 504, and 506 and color values ​​508, 510, and 512 are illustrated with reference to the RGB measurement 312 in Figure 3.

[0036] The intensity value 514 represents the intensity or brightness of the printer nozzle color color values ​​508, 510, and 512. The intensity value 514 is used to ensure that the printed color matches the desired uniform color value. By adjusting the intensity value 514, a consistent color density can be achieved throughout the printed image. The intensity value 514 is controlled by varying the amount of ink or toner ejected by the printer nozzle. By fine-tuning the intensity value 514, the system can compensate for variations in nozzle performance and ensure that each color is printed with the correct density. A further example of the intensity value 514 is illustrated with reference to the intensity value 310 in Figure 3.

[0037] To generate the lookup table 500, the system can print a target pattern (e.g., target pattern 302) containing a series of color patches of uniform or non-uniform shape. The number of color patches to print varies. For example, if N × N × N color patches are printed to sample the RGB space evenly, the total number of color patches depends on the value of N. If N is 9, 729 color patches are printed (9 × 9 × 9 = 729), and if N is 17, 4913 color patches are printed (17 × 17 × 17 = 4913). In some embodiments, RGB colors are represented by 3 bytes (RGB), with 1 byte (8 bits) assigned to each color channel. Each color channel is assigned a value between 0 and 255.

[0038] In some embodiments, the color patches are uniform squares with sides of at least 7 mm so that they can be scanned with a spectrophotometer, ensuring that the RGB sensor values ​​are representative. The target pattern is printed and measured by an RGB sensor built into the printer. The RGB values ​​read for each patch are recorded. The same target pattern can be measured with a spectrophotometer, and the spectral values ​​of each patch are converted to intensity. The combination of RGB values ​​and intensity values ​​is used to generate a lookup table (e.g., lookup table 314 in Figure 3). This lookup table can be stored by other resources in the printing system or in an external system.

[0039] Figure 5 shows an example of a lookup table 500 according to one or more embodiments. The components of the lookup table 500 shown in Figure 5 include color channels 502, 504, 506, color values ​​508, 510, 512, and intensity value 514. Other components of the lookup table 500 include components of a computer system 700, which will be described in more detail with reference to Figure 7. Other embodiments may include different components and / or additional components, or may be connected in different ways.

[0040] Color channels 502, 504, and 506 represent the individual color components that make up the final printed image. For example, color channels 502, 504, and 506 can represent red, green, and blue. Each color channel is responsible for a specific wavelength range in the visible spectrum, and the combination of these channels generates the entire color range in the printed image. Color values ​​508, 510, and 512 represent specific color measurements obtained from the printed image defined by color channels 502, 504, and 506. Further examples of color channels 502, 504, and 506 and color values ​​508, 510, and 512 are illustrated with reference to the RGB measurement 312 in Figure 3.

[0041] The intensity value 514 represents the intensity or brightness of the color values ​​508, 510, and 512 from the printer nozzle. The intensity value 514 is used to ensure that the printed colors match the desired uniform color values. By adjusting the intensity value 514, a consistent color density can be achieved throughout the printed image. The intensity value 514 is controlled by changing the amount of ink or toner ejected by the printer nozzle. By fine-tuning the intensity value 514, the system can compensate for variations in nozzle performance and ensure that each color is printed at the correct density. A further example of the intensity value 514 is illustrated with reference to the intensity value 310 in Figure 3.

[0042] Figure 6 is a flowchart illustrating a process for achieving uniform density in a solid area according to one or more embodiments. In some embodiments, the process in Figure 6 is performed using a printing system, for example, the printing system of environment 300, which is described in more detail with reference to Figure 3. In other embodiments, the process in Figure 6 is performed using components of computer system 700, which is described in more detail with reference to Figure 7. Similarly, other embodiments include different steps and / or additional steps, or are performed in a different order.

[0043] In step 602, the printing system receives a print job containing a set of solid color areas of an image to be printed by a set of printer nozzles in the printing system. This set of solid color areas is associated with a set of uniform color values. The printing system may include components such as print heads, ink tanks, and control circuits for managing the printing process. The print job may be received from a user interface, a network connection, or a storage device. These uniform color values ​​can be defined in a color space such as RGB (red, green, blue) or CMYK (cyan, magenta, yellow, black). In some embodiments, the printing system's software parses the print job file, extracts color information, and identifies the solid color areas that need to be processed.

[0044] In step 604, the printing system determines an array that includes one or more mappings of a set of uniform color values ​​to a set of density values ​​associated with that set of uniform color values. This set of density values ​​is measured using a spectrophotometer. In some embodiments, this array is a three-dimensional lookup table. The set of color values ​​may include a first channel, a second channel, and a third channel. The first channel may represent the red level, the second channel may represent the green level, and the third channel may represent the blue level. In some embodiments, this array is encoded in binary format. The lookup table can be stored in the printer's firmware or software for quick reference during the printing process.

[0045] In some embodiments, the printing system is a first printing system. This system can determine its arrangement by printing a set of targets by a second printing system. These targets are test prints (e.g., target pattern 302) with known color values ​​used to calibrate the system. In some embodiments, the first and second printing systems are different. Each target in the set of targets can be defined by a color value. The system uses one or more built-in sensors mounted on the second printing system to measure the set of targets and obtain the color value of each target. The built-in sensors (e.g., RGB sensors 306, 318) include color meters or other optical sensors that provide real-time feedback on the print output.

[0046] The system can use the spectrophotometer of the second printing system (e.g., spectrophotometer 304) to measure the color values ​​of a set of targets and obtain a set of spectral measurements for each target. Each spectral measurement in the set of spectral measurements can be associated with the intensity of light absorbed by the corresponding color value. The system can convert the set of spectral measurements into a set of density values. The system generates an array by aggregating the set of color values ​​of the target set and the corresponding density values ​​in the set of density values.

[0047] The system can smooth sets of color values ​​and density values. Smoothing can reduce noise in the sets of color values ​​and / or density values. For example, the system collects raw color and density values, but these values ​​may contain noise due to various factors such as sensor inaccuracies, environmental conditions, and inherent variability in the printing process. By applying smoothing algorithms such as Gaussian smoothing or moving average filters, noise can be reduced and ensure that the lookup table provides a stable and accurate mapping. The system can average noise while preserving important features by applying a Gaussian function to the data and weighting the values ​​based on their distance from a center point. In some embodiments, the system can average a certain number of adjacent data points. This can be implemented by iterating through the dataset and calculating the average of each point based on its neighborhood, thereby reducing the impact of outliers and random variability.

[0048] In some embodiments, the system interpolates a set of color values ​​and a set of density values ​​to generate an array according to a given set of values. Interpolation methods such as linear interpolation or spline interpolation can be used to fill gaps in a lookup table by estimating unknown values ​​between known data points, ensuring that the lookup table covers the entire range of possible color values. The system identifies the two nearest known color values ​​and their corresponding density values, and then calculates the intermediate unknown values ​​using a linear equation. Spline interpolation can be implemented using algorithms such as cubic splines. A cubic spline fits a cubic polynomial between each pair of known data points, ensuring continuity and smoothness at the data points.

[0049] In step 606, the system uses the determined array to obtain a template from the raster image processor of the printing system, configured to map a set of density values ​​for a uniform color value set to a set of intensity values ​​for a set of printer nozzles. This array can be stored within the raster image processor of the printing system. The template includes multiple bands, each containing a set of density for each color channel in the set of color values. The bands can be oriented horizontally with respect to the xyz axes or in other directions. In some embodiments, the raster image processor evaluates the intensity value for each printer nozzle in the set of printer nozzles based on the set of bands.

[0050] For each uniform color value, the raster image processor refers to an array to determine the corresponding density value. Using these density values, the raster image processor can calculate the appropriate density value for each printer nozzle. For example, the calculation can take into account factors such as the type of ink, the characteristics of the printing medium, and the specific function of the printer nozzle.

[0051] In step 608, using the acquired template, the system determines the intensity value of each printer nozzle in a set of printer nozzles based on the density value of the corresponding uniform color value for each solid color area in the set of color areas. For example, when a user submits a job to the printer, the raster image processor can use the density value to adjust the intensity of each printer nozzle.

[0052] In step 610, the system prints the image via the printing system according to the determined intensity values ​​of the set of printer nozzles. Each nozzle is capable of ejecting an amount of ink determined by the raster image processor using a density value that ensures uniform color density across all solid areas. The printer control software sends the calculated intensity values ​​to the print head, and the print head executes the print job according to the parameters determined by the raster image processor. Computer system

[0053] Figure 7 is a block diagram showing an exemplary computer system 700 according to one or more embodiments. In some examples, the computer system 700 includes one or more central processing units ("processors") 702, main memory 706, non-volatile memory 710, a network adapter 712 (e.g., a network interface), a video display 718, input / output devices 720, control devices 722 (e.g., a keyboard and pointing device), a drive unit 724 including a storage medium 726, and signal generation devices 730, all of which are communicatively connected to a bus 716. The bus 716 is illustrated as an abstraction representing one or more physical buses and / or point-to-point connections connected by appropriate bridges, adapters, or controllers. Therefore, in some examples, bus 716 includes the system bus, Peripheral Component Interconnect (PCI) bus or PCI-Express bus, HyperTransport or Industry Standard Architecture (ISA) bus, Small Computer System Interface (SCSI) bus, Universal Serial Bus (USB), IIC (I2C) bus, or the Institute of Electrical and Electronics Engineers (IEEE) standard 1394 bus (also known as "Firewire").

[0054] In some examples, the computer system 700 shares a computer processor architecture similar to that of a desktop computer, tablet computer, personal digital assistant (PDA), mobile phone, game console, music player, wearable electronic device (e.g., watch or fitness tracker), network-connected ("smart") device (e.g., television or home assistant device), virtual reality / augmented reality system (e.g., head-mounted display), or other electronic device capable of executing (sequentially or otherwise) a set of instructions that specify the actions to be performed by the computer system 700.

[0055] Although the main memory 706, non-volatile memory 710, and storage medium 726 (also called “machine-readable medium”) are shown as a single medium, the terms “machine-readable medium” and “storage medium” should be interpreted to include a single or multiple medium (e.g., a centralized / distributed database and / or associated caches and servers) that can store one or more sets of instructions 728. The terms “machine-readable medium” and “storage medium” should be interpreted to include any medium that can store, encode, or transmit a set of instructions for execution by the computer system 700.

[0056] Generally, routines performed to implement embodiments of the present disclosure can be implemented as part of an operating system or a particular application, component, program, object, module, or instruction sequence (collectively referred to as a “computer program”). A computer program typically includes one or more sets of instructions (e.g., instructions 704, 708, 728) set at different points in time in various memory and storage devices within a computing device. When these instructions are read and executed by one or more processors 702, they cause the computer system 700 to perform operations to execute elements, including various aspects of the present disclosure.

[0057] Furthermore, although the embodiments are described in the context of a fully functional computing device, those skilled in the art will understand that various embodiments can be distributed as various forms of program products. This disclosure applies regardless of the specific type of machine or computer-readable medium used to actually carry out the distribution.

[0058] Further examples of machine-readable storage media, machine-readable media, or computer-readable media include volatile and non-volatile memory 710, floppy disks and other removable disks, hard disk drives, optical disks (e.g., Compact Disc Read-Only Memory (CD-ROM), Digital Versatile Disk (DVD)), and transmission media such as digital or analog communication links.

[0059] The network adapter 712 enables the computer system 700 to mediate data with entities outside of the computer system 700 within the network 714 via any communication protocol supported by the computer system 700 and the external entity. In some examples, the network adapter 712 includes network adapter cards, wireless network interface cards, routers, access points, wireless routers, switches, multilayer switches, protocol converters, gateways, bridges, bridge routers, hubs, digital media array receivers, and / or repeaters.

[0060] In some embodiments, the network adapter 712 includes a firewall that controls and / or manages permission for access / proxy to data in a computer network and tracks various levels of trust between different machines and / or applications. In some examples, the firewall is any number of modules having any combination of hardware and / or software components (e.g., to regulate traffic flow and resource sharing between these entities) that can enforce a predetermined set of access rights between a particular set of machines and applications, between machines and machines, and / or between applications. In some embodiments, the firewall further manages and / or accesses access control lists that describe permission details, including access rights and manipulation rights to objects by individuals, machines, and / or applications, and the circumstances under which those permissions become effective.

[0061] In some embodiments, the technologies described herein are implemented by programmable circuits (e.g., one or more microprocessors), software and / or firmware, dedicated hardwired (i.e., non-programmable) circuits, or a combination thereof. In some examples, the dedicated circuits take the form of one or more application-specific integrated circuits (ASICs), programmable logic devices (PLDs), or field-programmable gate arrays (FPGAs).

[0062] The descriptions and drawings in this specification are illustrative and should not be construed as limiting. Numerous specific details are provided to enable a full understanding of this disclosure. However, in some cases, well-known details are omitted to avoid obscuring the description. Furthermore, various modifications are possible without departing from the scope of the embodiments.

[0063] The terms used herein generally have their ordinary meanings in the art, in the context of this disclosure, and in the specific context in which each term is used. Specific terms used to describe this disclosure are described above or elsewhere in this specification to provide practitioners with further guidance regarding the description of this disclosure. For convenience, certain terms may be highlighted, for example, using italics and / or quotation marks. The use of highlighting does not affect the scope and meaning of the terms, which are the same in the same context, with or without highlighting. It will be understood that the same thing can be expressed in multiple ways. It will be recognized that “memory” is a form of “storage,” and that these terms may be used interchangeably in some cases.

[0064] Accordingly, alternative languages ​​and synonyms may be used for one or more of the terms described herein, but no special significance is placed on whether or not a term is described or explained in detail herein. Certain terms are accompanied by synonyms. The inclusion of one or more synonyms does not preclude the use of other synonyms. Nowhere in this specification is the use of examples, including examples of terms discussed herein, for illustrative purposes only and is not intended to further limit the scope and meaning of this disclosure or the terms illustrated herein. Similarly, this disclosure is not limited to the various embodiments described herein.

[0065] The embodiments and modifications shown and described herein are merely illustrative of the principles of the present invention, and it should be understood that those skilled in the art can make various modifications.

Claims

1. A method for correcting density variations in solid areas of an image, comprising the following steps: A printing system receives a print job comprising a set of solid color areas of an image to be printed by a set of printer nozzles of the printing system, wherein the set of solid color areas is associated with a set of uniform color values; The printing system determines an array comprising one or more mappings between a set of uniform color values ​​and a set of density values ​​associated with the set of uniform color values, wherein the set of density values ​​is measured using a spectrophotometer; A step of obtaining a template from the raster image processor of the printing system using the determined array, configured to map the set of density values ​​for the uniform color values ​​to a set of intensity values ​​for the set of printer nozzles; A step of determining the intensity value of each printer nozzle in the set of printer nozzles based on the density value of the corresponding uniform color value of each solid color area in the set of color areas, using the acquired template; and The step of printing the image via the printing system according to the determined intensity values ​​of the set of printer nozzles. A method that includes [a certain feature].

2. The printing system is a first printing system, and the step of determining the arrangement is: The second printing system is a step of printing a set of targets, Each target in the set of targets is defined by a color value, in steps; A step of measuring the set of targets using one or more sensors embedded in the second printing system and obtaining the color value of each target: A step of measuring the color values ​​of the set of targets using the spectrophotometer of the second printing system to obtain a set of spectral measurement values ​​for each target, Step 1: Each spectral measurement in the set of spectral measurements is associated with the intensity of light absorbed by the corresponding color value; The steps of converting the set of spectral measurements into the set of concentration values: and A step of generating the array by aggregating the set of color values ​​and the corresponding density values ​​of the set of density values ​​of the set of targets, The method according to claim 1, comprising:

3. The method according to claim 2, wherein the first printing system and the second printing system are different.

4. A step of smoothing the set of color values ​​and the set of density values, The smoothing process reduces one or more noises from the set of color values ​​or the set of density values, The method according to claim 2, comprising:

5. A step of generating the array by interpolating the set of color values ​​and the set of density values ​​according to a predetermined set of values, The method according to claim 2, comprising: A method that includes this.

6. The method according to claim 1, wherein the array is a three-dimensional lookup table.

7. The set of color values ​​includes a first channel, a second channel, and a third channel. The first channel shows a red level, The second channel shows a green level, and The third channel indicates a blue level. The method according to claim 1.

8. A printing system for correcting density fluctuations in a solid area, comprising at least one hardware processor and at least one non-temporary memory, When the non-temporary memory is executed by the at least one hardware processor, the printing system performs the following actions: The operation of the printing system receiving a print job which includes a set of solid color areas of an image to be printed by a set of printer nozzles of the printing system, The operation is such that the set of solid color regions is associated with a set of uniform color values; The printing system determines an array which includes one or more mappings between a set of uniform color values ​​and a set of density values ​​associated with the set of uniform color values, The set of concentration values ​​is measured using a spectrophotometer; An operation to obtain from the raster image processor of the printing system a template configured to map the set of density values ​​of the uniform color values ​​to the set of intensity values ​​of the set of printer nozzles, using the determined array; Using the acquired template, the operation of determining an intensity value for each printer nozzle in the set of printer nozzles based on the density value of the corresponding uniform color value of each solid color area in the set of color areas; and The operation of printing the image via the printing system according to the determined intensity values ​​of the set of printer nozzles, Stores the command to execute. Printing system.

9. The printing system according to claim 8, wherein the array is stored in the raster image processor of the printing system.

10. The printing system according to claim 9, wherein the template includes a set of bands that contain a set of densities for each color channel of the set of color values.

11. The printing system according to claim 10, wherein the raster image processor is configured to evaluate the intensity value of each printer nozzle in the set of printer nozzles based on the set of bands.

12. The printing system according to claim 8, wherein the sequence is encoded in binary format.

13. The printing system according to claim 8, wherein the operation of determining the intensity value of each printer nozzle in the set of printer nozzles is performed by the raster image processor of the printing system.

14. The printing system according to claim 8, wherein the array is a three-dimensional lookup table.

15. A printing system for correcting density fluctuations in solid areas, Multiple printer nozzles, A plurality of printer nozzles, each of which is configured to print an image according to a corresponding intensity value; An array including one or more mappings that map a set of color values ​​to a set of density values ​​of the set of color values, The set of concentration values ​​within the array is measured using a spectrophotometer; and The following process: A process by which the printing system receives a print job including a set of solid color areas in an image to be printed by a set of printer nozzles of the printing system, The process in which the set of solid color regions is associated with a set of uniform color values; A process of determining the corresponding intensity value for each of the plurality of printer nozzles based on the density value of the corresponding uniform color value for each solid color region in the set of color regions using the aforementioned array; and A process of printing the image according to the determined intensity values ​​of the plurality of printer nozzles, A processing circuit configured to perform the following: A printing system equipped with the following features.

16. The printing system according to claim 15, wherein the array is a three-dimensional lookup table.

17. The set of color values ​​includes a first channel, a second channel, and a third channel. The first channel shows a red level, The second channel shows a green level, and The third channel indicates a blue level. The printing system according to claim 15.

18. The printing system according to claim 15, wherein the array is stored in the raster image processor of the printing system.

19. The printing system according to claim 18, wherein the raster image processor is configured to evaluate the corresponding intensity value of each printer nozzle in the set of printer nozzles.

20. The printing system according to claim 15, wherein the process of determining the intensity value of each printer nozzle in the set of printer nozzles is performed by the raster image processor of the printing system.

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