A method, apparatus and storage medium for color printing on curved surfaces

Abstract

This invention discloses a method, device, and storage medium for color printing on curved surfaces. The method includes the following steps: S1, acquiring curved surface data; S2, constructing a mathematical model that accurately represents the geometric features of the curved surface; S3, obtaining the printing starting point of the digital printer; S4, obtaining the printing information of the printhead; S5, generating printing data for the corresponding curved surface from the original image by calculating the projection; S6, sending the printing data calculated in step S5 to the printer to begin curved surface printing. This invention solves the problem that flatbed printers cannot print curved surfaces, achieving the goal of generating printing data for the corresponding curved surface from the original image by calculating the projection, thus enabling curved surface printing using a flatbed printer. Furthermore, this invention is highly versatile and flexible. It is applicable to various polygonal curved surfaces, whether regular or irregular, and the printhead movement plane can be flexibly set as needed to meet different printing tasks and creative design requirements.

Description

Technical Field

[0001] This invention relates to the field of printer technology, and in particular to a method, apparatus and storage medium for color printing on curved surfaces. Background Technology

[0002] In the current digital printing field, most mainstream digital printers are designed based on planar printing media. Their conventional operating mode involves a carriage with a printhead reciprocating on a linear guide rail to print images on flat media such as paper and film. This mechanical structure and printing method already achieves high precision and efficiency in planar printing tasks, meeting many common printing needs, such as document printing and planar image output.

[0003] However, new challenges arise when printing on uneven, curved media. Due to the irregularity of the surface, the distances, angles, and other geometric relationships between the printhead and its various positions are constantly changing, a stark contrast to the relatively fixed and regular positional relationship between the printhead and the media in flat printing. If existing flat printing data and methods are directly applied, the ink droplets ejected from the printhead will inevitably fail to land accurately at the expected positions, leading to severe color registration errors and ultimately affecting the quality of the printed image, potentially even preventing the entire printing task from achieving its intended effect. Furthermore, considering the premise of not significantly altering the existing printer's mechanical structure, it's impossible to directly adapt to curved surface printing through large-scale hardware adjustments (such as changing the guide rail shape or adding complex surface adaptation mechanisms). Therefore, solutions must be sought at the print data level. By subtly and precisely modifying the print data, the limitations of the mechanical structure can be compensated for, ensuring that ink droplets from different color nozzles of the printhead land at the expected positions on the uneven curved surface, achieving correct color registration and high-quality print output.

[0004] Therefore, there is an urgent need for a method for color printing of curved surfaces that can generate corresponding curved surface printing data from the original image by calculating the projection, thereby enabling the use of a flatbed printer for curved surface printing. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, the present invention provides a method, apparatus and storage medium for color printing on curved surfaces.

[0006] The technical solution of this invention is implemented as follows:

[0007] A method for color printing on curved surfaces includes the following steps:

[0008] S1, collect surface data, use image recognition technology to measure the uneven surface to be printed, and obtain the three-dimensional coordinate data of each point on the surface;

[0009] S2, using mathematical modeling algorithms, constructs a mathematical model that can accurately characterize the geometric features of the surface;

[0010] S3, obtain information about the digital printer's print start point, the total number of passes for the printed image, and the scanning range for each pass;

[0011] S4, obtain the printing information of the printhead through the digital printer, specifically including the number of printheads, the geometric arrangement of each printhead, the number of nozzles, the ink color of each nozzle, and the geometric arrangement of each nozzle;

[0012] S5, based on steps S3 and S4, generate the corresponding surface printing data from the original image by calculating the projection;

[0013] S6. Send the print data calculated in step S5 to the printer to start surface printing.

[0014] Preferably, step S1 specifically involves using laser scanning technology to scan the curved surface line by line with a laser beam, capturing the reflected light signal through a high-precision optical signal receiving device, and accurately obtaining the three-dimensional coordinate data of each point on the curved surface based on the time difference principle of light propagation and the information on the change of reflected light intensity; or using structured light projection technology to project a preset specific light pattern onto the curved surface, and meticulously calculating the spatial position details of each point based on the deformation characteristics of the light pattern on the curved surface using the principle of triangulation.

[0015] Preferably, step S2 specifically involves using mathematical modeling algorithms to construct a mathematical model that can accurately characterize the geometric features of the surface through methods based on surface fitting or spline functions.

[0016] Preferably, the modeling accuracy of the mathematical model matches the printing accuracy, and the coordinate interval of each polygon vertex is less than or equal to the interval between adjacent printed pixels.

[0017] Preferably, step S3 specifically involves obtaining the printing trajectory of the curved image printed on a plane based on the drive of the printer's print head, and determining the printing start point, the total number of passes of the printed image, and the scanning range of each pass.

[0018] Preferably, the projection calculation method is as follows:

[0019] S51, through a mathematical model, obtain the vertex coordinates of the entire polygon's surface, specifically including the coordinates of all vertices on the surface;

[0020] S52, Calculate the plane of nozzle motion. To accurately describe the plane of nozzle motion, the following plane equation form is used. Let there be two planes, whose equations are denoted as:

[0021] Ax + By + Cz + D = 0.

[0022] A′x+B′y+C′z+D′=0,

[0023] Where (A,B,C) and (A′,B′,C′) are the normal vectors of the plane, and D and D′ are constant terms;

[0024] S53, obtain the printing resolution of the original image;

[0025] S54, for any given point P(x,y,z) on the surface, the perpendicular distance d from point P to this plane can be calculated using the following formula:

[0026] d=∣Ax+By+Cz+D∣A2+B2+C2;

[0027] The formula for calculating the perpendicular distance d′ from another point P′(x,y,z) on the surface to this plane is:

[0028] d′=A′2+B′2+C′2∣A′x+B′y+C′z+D′∣;

[0029] S55. Calculate the distance dd′, and move the point P(x,y,z)P′(x,y,z) on the surface towards the plane along the direction of the plane normal vector (A,B,C)(A′,B′,C′), by the distance dd′ to obtain the projection point P. m (x m ,y m ,z m )P m ′(x m ,y m ,z m The coordinates of the projection point are given. The direction of movement is the opposite of the vector (A,B,C)(A′,B′,C′), i.e., (-A,-B,-C)(-A′,-B′,-C′). Therefore, the formula for calculating the coordinates of the projection point is:

[0030] x m = x + AA² + B² + C² · dx m =x + A² + B² + C²A·d;

[0031] y m =y + BA² + B² + C² · dy m =y + A² + B² + C²B·d;

[0032] z m =y + CA² + B² + C² · dz m =y + A² + B² + C²C·d;

[0033] S56, Apply step S55 to all coordinate vertices obtained in step S51;

[0034] S57. Based on the parameters of step S3 and the projection point positions of all printing planes, the content of the original image pixels is mapped to each nozzle at each pass position of the printhead to generate printing data.

[0035] A curved surface printing color matching device includes at least one processor, at least one memory, and computer program instructions stored in the memory. When the computer program instructions are executed by the processor, the aforementioned curved surface printing color matching method is implemented.

[0036] A storage medium storing computer program instructions, characterized in that when the computer program instructions are executed by a processor, the aforementioned method for color matching in surface printing is implemented.

[0037] This invention solves the problem of flatbed printers being unable to print curved surfaces. It achieves the goal of generating corresponding curved surface printing data from the original image through calculated projection, thus enabling curved surface printing using a flatbed printer. Furthermore, this invention boasts high versatility and flexibility. It is applicable to various polygonal curved surfaces, both regular and irregular. The printhead movement plane can be flexibly set as needed to meet different printing tasks and creative design requirements, adapting to diverse application scenarios and possessing scalability. It can be combined with images of different resolutions, easily adapting to changes in printing technology and precision requirements. Attached Figure Description

[0038] Figure 1 This is a schematic diagram of a curved surface printing color matching method according to the present invention. Detailed Implementation

[0039] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, exemplary embodiments will be described in detail below, examples of which are illustrated in the accompanying drawings. In the following description relating to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of methods and systems consistent with some aspects of this application as detailed in the appended claims.

[0040] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0041] Example 1

[0042] This invention provides a method for color matching in curved surface printing, comprising the following steps:

[0043] S1, collect surface data, use image recognition technology to measure the uneven surface to be printed, and obtain the three-dimensional coordinate data of each point on the surface;

[0044] In step S1, advanced and precise measurement techniques are employed to acquire surface data. Specifically, this can be achieved through two preferred methods: First, laser scanning technology is used, employing a high-energy-density, highly directional laser beam to scan the surface line by line, while simultaneously using a high-precision optical signal receiver capable of sensitively capturing reflected light signals. Based on the time difference principle of light propagation and information such as changes in reflected light intensity, a professional data processing algorithm accurately acquires the three-dimensional coordinate data of each point on the surface. Second, structured light projection technology is used to project a pre-set specific light pattern onto the surface. Due to the unevenness of the surface, the light pattern will deform accordingly. Subsequently, based on the deformation characteristics of the light pattern on the surface, and using mature triangulation principles, precise geometric calculations are used to meticulously deduce the spatial position details of each point. Through these methods, it is ensured that the acquired surface data comprehensively and accurately reflects the actual geometric shape of the surface, laying a solid data foundation for subsequent steps.

[0045] S2 uses advanced mathematical modeling algorithms to construct a mathematical model that can accurately represent the geometric features of the surface;

[0046] In step S2, advanced mathematical modeling algorithms are employed, specifically mature mathematical methods such as surface fitting or spline functions, to deeply analyze and process the 3D coordinate data of various points on the large number of surfaces obtained in step S1. Through surface fitting, based on the distribution pattern of the data points, the most suitable mathematical function is found to describe the overall shape of the surface; or, using spline functions, the surface is divided into multiple local regions, and a suitable function expression is constructed in each region, so that the overall model can accurately reflect the complex shape of the surface while ensuring smooth transitions between different local regions. The mathematical model constructed in this way can accurately characterize the geometric features of the surface, covering key information such as curvature changes, concavity and convexity distribution, and overall shape category. Furthermore, the modeling accuracy and printing accuracy of this mathematical model must match, ensuring that the coordinate interval of each polygon vertex in the model is less than or equal to the adjacent interval of the printed pixels. This provides a reliable basis for subsequent operations such as generating printing data based on the model, avoiding printing errors caused by differences in accuracy.

[0047] S3, obtain information about the digital printer's print start point, the total number of passes for the printed image, and the scanning range for each pass;

[0048] In step S3, the printer's printhead drive mechanism is analyzed in depth. By reading relevant parameters and control logic within the printer, information related to the printing trajectory when simulating a curved image as a flat surface for printing is obtained. Specifically, the printing start point is determined, i.e., the initial position coordinates where the printhead begins the printing operation; the total number of passes for the printed image is determined, which reflects the number of times the printhead scans the image during the entire printing process, indicating the number of layers and the degree of coverage; and the scanning range of each pass is determined, i.e., the area that the printhead can cover in each scan, including the horizontal and vertical intervals. This information will serve as an important basis for subsequently generating printing data adapted to the curved surface and planning the printhead movement path, ensuring that the printing data accurately corresponds to the actual working conditions of the printer and achieves a reasonable match between the printed image and the curved surface.

[0049] S4, obtain the printing information of the printhead through the digital printer, specifically including the number of printheads, the geometric arrangement of each printhead, the number of nozzles, the ink color of each nozzle, and the geometric arrangement of each nozzle;

[0050] In step S4, data interaction is performed with the digital printer to obtain comprehensive and detailed printing information from its printheads. First, the number of printheads is determined, as different numbers affect printing efficiency and color combinations. Next, the geometric arrangement of each printhead is understood, such as whether they are arranged in a straight line, matrix, or other specific layout on the printing device, which relates to the printhead coverage and printing sequence. The number of nozzles in each printhead is counted, as this directly determines the ink volume ejected per unit time and the printing resolution. The ink color of each nozzle is determined for accurate color registration calculations later. Simultaneously, the geometric arrangement of each nozzle is clarified, such as whether the nozzles are uniformly distributed on the printhead surface or distributed according to a specific pattern, which significantly affects the droplet distribution on curved surfaces and the color mixing effect. By comprehensively acquiring this printhead printing information, sufficient basis is provided for generating accurate curved surface printing data based on printhead characteristics, ensuring accurate color and pattern presentation during the printing process.

[0051] S5, based on steps S3 and S4, generate the corresponding surface printing data from the original image by calculating the projection;

[0052] When generating print data, the process first reads the surface mathematical model file from the storage module and extracts the vertex coordinate information of the polygonal surface. Then, according to the rules set by the plane equations, the relevant parameters (normal vector and constant terms) of the printhead motion plane are determined. Next, the print resolution of the original image is determined (this can be obtained through image file properties or print job settings). Afterward, for each vertex coordinate on the surface, the point-to-plane distance and projection point coordinates are calculated sequentially, and the projection point coordinate calculation method is applied to all vertices. Finally, based on the obtained printer information (print start point, total number of passes, scan range per pass, etc.), a specialized data mapping algorithm accurately maps the pixel content of the original image to each nozzle at each pass position of the printhead, generating a complete print data file, which is stored in a buffer area readable by the printer.

[0053] S6. Send the print data calculated in step S5 to the printer to start surface printing.

[0054] In step S6, the calculated print data from step S5 is sent to the digital printer's control system via the data transmission interface. Upon receiving this data, the printer's control system, based on its internal preset printing logic and control algorithm, drives the printhead to perform point-by-point, line-by-line, and pass-by-pass printing operations on the uneven curved surface according to the corresponding motion trajectory and inkjet parameters. Throughout the printing process, the printhead accurately controls the inkjet timing, droplet size, and color of each nozzle based on the print data, ensuring accurate color registration at all positions on the curved surface, ultimately presenting a high-quality, expected printed image and completing the uneven curved surface printing task.

[0055] Preferably, step S1 specifically involves using laser scanning technology to scan the curved surface line by line with a laser beam, capturing the reflected light signal through a high-precision optical signal receiving device, and accurately obtaining the three-dimensional coordinate data of each point on the curved surface based on the time difference principle of light propagation and the information on the change of reflected light intensity; or using structured light projection technology to project a preset specific light pattern onto the curved surface, and meticulously calculating the spatial position details of each point based on the deformation characteristics of the light pattern on the curved surface using the principle of triangulation.

[0056] Preferably, the modeling accuracy of the mathematical model matches the printing accuracy, and the coordinate interval of each polygon vertex is less than or equal to the interval between adjacent printed pixels.

[0057] Preferably, step S3 specifically involves obtaining the printing trajectory of the curved image printed on a plane based on the drive of the printer's print head, and determining the printing start point, the total number of passes of the printed image, and the scanning range of each pass.

[0058] Preferably, the projection calculation method is as follows:

[0059] S51, through a mathematical model, obtain the vertex coordinates of the entire polygon's surface, specifically including the coordinates of all vertices on the surface;

[0060] S52, Calculate the plane of nozzle motion. To accurately describe the plane of nozzle motion, the following plane equation form is used. Let there be two planes, whose equations are denoted as:

[0061] Ax + By + Cz + D = 0.

[0062] A′x+B′y+C′z+D′=0,

[0063] Where (A,B,C) and (A′,B′,C′) are the normal vectors of the plane, and D and D′ are constant terms;

[0064] S53, obtain the printing resolution of the original image;

[0065] S54, for any given point P(x,y,z) on the surface, the perpendicular distance d from point P to this plane can be calculated using the following formula:

[0066] d=∣Ax+By+Cz+D∣A2+B2+C2;

[0067] The formula for calculating the perpendicular distance d′ from another point P′(x,y,z) on the surface to this plane is:

[0068] d′=A′2+B′2+C′2∣A′x+B′y+C′z+D′∣;

[0069] S55. Calculate the distance dd′, and move the point P(x,y,z)P′(x,y,z) on the surface towards the plane along the direction of the plane normal vector (A,B,C)(A′,B′,C′), by the distance dd′ to obtain the projection point P. m (x m ,y m ,z m )P m ′(x m ,y m ,z m The coordinates of the projection point are given. The direction of movement is the opposite of the vector (A,B,C)(A′,B′,C′), i.e., (-A,-B,-C)(-A′,-B′,-C′). Therefore, the formula for calculating the coordinates of the projection point is:

[0070] x m = x + AA² + B² + C² · dx m =x + A² + B² + C²A·d;

[0071] y m =y + BA² + B² + C² · dy m =y + A² + B² + C²B·d;

[0072] z m =y + CA² + B² + C² · dz m =y + A² + B² + C²C·d;

[0073] S56, Apply step S55 to all coordinate vertices obtained in step S51;

[0074] S57. Based on the parameters of step S3 and the projection point positions of all printing planes, the content of the original image pixels is mapped to each nozzle at each pass position of the printhead to generate printing data.

[0075] Preferably, during curved surface printing in step S6, a high-definition camera is used to capture images of the print head's printing position, ink droplet landing point, and printed portion on the curved surface in real time. Through image recognition and analysis technology, the images are compared with preset printing data. If deviations or anomalies are found, printing is immediately paused. Printing parameters are adjusted based on the analysis results, and then printing continues. This achieves real-time visual monitoring and dynamic adjustment of the curved surface printing process, ensuring that the printing task is completed smoothly and meets quality standards.

[0076] For example, consider printing high-resolution images on a textured, irregularly shaped sculpted surface. When printing on raised facial features, the surface curvature varies significantly. To ensure ink droplets land accurately and to prevent ink splattering or deviation from the intended landing point due to excessive printhead movement, the printhead speed needs to be appropriately reduced. Assuming the printhead speed is initially set to 50 mm / s on a relatively flat curved surface, when printing on the raised bridge of the nose, the speed is reduced to 20 mm / s. This allows the printhead more time to accurately eject ink droplets at the correct position, ensuring the image is clearly and precisely rendered even on complex raised areas.

[0077] When printing on the recessed areas of clothing folds, the complex relative positional relationship between the printhead and the curved surface must also be taken into account. The ink droplet landing point needs to be carefully controlled, and the speed must be slowed down, possibly adjusted to 15 millimeters per second, to ensure that the ink droplets can be smoothly sprayed onto the recessed area and evenly distributed, so as to achieve a high-quality printing effect.

[0078] Conversely, when the printhead moves to a relatively flat, large area with little curvature, such as the back of a sculpture, the printhead movement speed can be increased appropriately to improve printing efficiency, for example, to 60 millimeters per second. This allows the printing of this area to be completed faster without affecting print quality.

[0079] In color curved surface printing, different colored inks differ in their composition, viscosity, and other physicochemical properties, requiring adjustments to the inkjet frequency accordingly. For example, when printing an advertising image containing a large amount of red elements onto a curved outdoor billboard, the red ink may have a slightly higher viscosity than other colors. To ensure that the red ink droplets are ejected evenly and stably and accurately registered with other colors, the inkjet frequency of the nozzle corresponding to the red ink needs to be appropriately reduced.

[0080] Assuming the original inkjet frequency of the blue ink nozzle is 1000 pulses per second (this frequency allows the blue ink to achieve a good jetting effect on the current curved surface and printing environment), while the red ink, due to viscosity issues, has its corresponding nozzle inkjet frequency adjusted to 800 pulses per second, so that the size of the red ink droplets, jetting speed, etc., can match the other colors, ultimately achieving a bright and accurate color registration effect for the entire advertising pattern.

[0081] Preferably, in step S53, when the original image has different resolutions on the curved surface, the image is divided into regions of different resolutions. Then, different mapping strategies are used to adapt to the curved surface for different regions. Finally, the parts are merged together by a fusion algorithm to generate printing data. This can ensure the overall printing effect while making full use of the various resolution information of the original image, thereby improving the quality and sense of layering of the printed image.

[0082] For example, on the curved surface of an electronic product's casing, which has a certain curvature and features areas for function buttons, brand logos, and large areas of textured decorations, patterns are printed. The image material includes high-resolution brand logos and low-resolution textured patterns.

[0083] Image segmentation involves separating clear and refined brand logos, such as trademark text and unique graphic symbols, with a resolution of 600 pixels per inch. This requires precise representation of design details and color accuracy. These high-resolution areas are then used in the print data generation stage. Leveraging the printhead's high-precision printing capabilities, each pixel of the logo is precisely mapped onto the corresponding position on the curved surface of the casing through accurate projection calculations. For example, to ensure sharp and clear edges and uniform color filling of the trademark text, parameters such as the printhead's ink jet angle, frequency, and movement speed are meticulously adjusted based on the thickness and direction of the strokes, ensuring that each ink droplet accurately creates a high-quality logo effect.

[0084] For low-resolution textures, such as simple matte textures that only need to convey the general light and shadow effects and tactile feel (around 100 pixels per inch), an adaptation method based on the overall characteristics of the texture is used. The texture is viewed as a collection of pattern elements with certain repetitive patterns and directions. Based on the curvature and shape of the outer shell, it is mapped to larger unit areas, allowing the texture to spread naturally on the curved surface. The printhead can move relatively quickly within these areas to print, rapidly covering large textured areas while ensuring the overall matte texture and light and shadow effects are still present.

[0085] The two elements are merged: after the brand logo and texture pattern are printed separately, a fusion operation is performed at their junction. A color mixing algorithm is used to gradually change the ink droplet color ratio within a certain width transition area, based on the color values ​​at the logo edge and texture start point. This allows for a natural transition between the logo and texture, creating a unified design that highlights the high definition and importance of the brand logo while showcasing the decorative nature of the texture pattern. Together, they create a beautiful curved surface printing effect that meets product design requirements.

[0086] These examples demonstrate that multi-resolution image adaptation and fusion solutions can fully utilize the resolution characteristics of different parts of the original image, combined with the surface shape and printing requirements, to achieve high-quality, visually appealing color matching effects for curved surface printing.

[0087] In this embodiment, the image segmentation algorithm includes a threshold segmentation algorithm, a region growing-based segmentation algorithm, or the edge detection segmentation algorithm.

[0088] In this embodiment, the threshold segmentation algorithm divides image pixels into different categories according to their gray values ​​by setting one or more gray thresholds. For example, it can distinguish parts with obvious gray differences between high-resolution and low-resolution regions, which is suitable for simple cases where the gray difference between the target and the background in the image is large.

[0089] In this embodiment, the region-growing segmentation algorithm starts from some seed points in the image and continuously merges adjacent pixels according to certain similarity criteria (such as similarity in pixel grayscale, color, etc.) to gradually grow into regions with similar features. It can be used to identify continuous high-resolution or low-resolution regions in an image, such as distinguishing between the main subject and background decoration in an art poster example, which are regions with similar continuous features.

[0090] In this embodiment, the edge detection and segmentation algorithm uses edge information with drastic changes in pixel grayscale in the image to determine the boundaries of different regions. Common operators such as Sobel and Canny can detect the contours of objects in the image and help to divide parts with different high and low resolutions. It is often used in situations where it is necessary to accurately define different detail areas of the image.

[0091] A curved surface printing color matching device includes at least one processor, at least one memory, and computer program instructions stored in the memory. When the computer program instructions are executed by the processor, the aforementioned curved surface printing color matching method is implemented.

[0092] A storage medium storing computer program instructions, which, when executed by a processor, implement the aforementioned method for color matching in surface printing.

[0093] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for color matching in curved surface printing, characterized in that, Includes the following steps: S1, collect surface data, use image recognition technology to measure the uneven surface to be printed, and obtain the three-dimensional coordinate data of each point on the surface; S2, using mathematical modeling algorithms, constructs a mathematical model that can accurately characterize the geometric features of the surface; S3, obtain information about the digital printer's print start point, the total number of passes for the printed image, and the scanning range for each pass; S4, obtain the printing information of the printhead through the digital printer, specifically including the number of printheads, the geometric arrangement of each printhead, the number of nozzles, the ink color of each nozzle, and the geometric arrangement of each nozzle; S5, based on steps S3 and S4, generate the corresponding surface printing data from the original image by calculating the projection; S6, send the print data calculated in step S5 to the printer and start surface printing; The projection calculation method is as follows: S51, through a mathematical model, obtain the vertex coordinates of the entire polygon's surface, specifically including the coordinates of all vertices on the surface; S52, Calculate the plane of nozzle motion. To accurately describe the plane of nozzle motion, the following plane equation form is used. Let there be two planes, whose equations are denoted as: Ax + By + Cz + D = 0. A'x+B'y+C'z+D'=0, Where (A,B,C) and (A´,B´,C´) are the normal vectors of the plane, and D and D´ are constant terms; S53, obtain the printing resolution of the original image; S54, For any given point P(x,y,z) on the surface, the perpendicular distance d from point P to this plane can be calculated using the following formula: d=∣Ax+By+Cz+D∣A²+B²+C²; The formula for calculating the perpendicular distance d' from another point P´(x,y,z) on the surface to this plane is: d´=A´²+B´²+C´²∣A´x+B´y+C´z+D´∣; S55. Calculate the distance dd', and move the point P(x,y,z) on the surface towards the plane along the direction of the plane normal vector (A,B,C). The projection point P is obtained by moving the point P'(x,y,z) on the surface by the distance dd'. m (x m ,y m ,z m )P m ´(x m ,y m ,z m The coordinates of the projection point are determined by the direction of movement, which is the opposite of the vector (A,B,C), i.e., (-A,-B,-C). Therefore, the formula for calculating the coordinates of the projection point is: x m =x+AA²+B²+C²·dx m =x+A²+B²+C²A·d ; the m =y+BA2+B2+C2·dy m =y+A2+B2+C2B·d ! z m =y+CA²+B²+C²·dz m =y+A²+B²+C²C·d; S56, Apply step S55 to all coordinate vertices obtained in step S51; S57. Based on the parameters of step S3 and the projection point positions of all printing planes, the content of the original image pixels is mapped to each nozzle at each pass position of the printhead to generate printing data.

2. The method for color matching in curved surface printing according to claim 1, characterized in that, Specifically, step S1 involves using laser scanning technology to scan the curved surface line by line with a laser beam, capturing the reflected light signal through a high-precision optical signal receiving device, and accurately obtaining the three-dimensional coordinate data of each point on the curved surface based on the time difference principle of light propagation and the information on the change in the intensity of reflected light.

3. The method for color matching in curved surface printing according to claim 1, characterized in that, Specifically, step S2 involves using mathematical modeling algorithms, through methods based on surface fitting or spline functions, to construct a mathematical model that can accurately characterize the geometric features of the surface.

4. The method for color matching in curved surface printing according to claim 3, characterized in that, The mathematical model's modeling accuracy matches its printing accuracy, and the coordinate interval of each polygon vertex is less than or equal to the interval between adjacent printed pixels.

5. The method for color matching in curved surface printing according to claim 1, characterized in that, Specifically, step S3 involves obtaining the printing trajectory of the curved image printed on a flat surface based on the drive of the printer's print head, and determining the printing start point, the total number of passes of the printed image, and the scanning range of each pass.

6. A curved surface printing color matching device, characterized in that, It includes at least one processor, at least one memory, and computer program instructions stored in the memory, which, when executed by the processor, implement the method described in any one of claims 1-5.

7. A storage medium storing computer program instructions thereon, characterized in that, The method described in any one of claims 1-5 is implemented when the computer program instructions are executed by the processor.

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