A method, apparatus and equipment for generating frequency modulation (FM) screens in screen printing.

Abstract

This invention provides a method, apparatus, and device for generating a frequency modulation (FM) halftone screen in halftone image processing. The method includes: obtaining a target threshold matrix, a nearest neighbor aggregation operator matrix, and an inter-point diffusion operator matrix to be assigned values; obtaining an intermediate matrix based on the nearest neighbor aggregation operator matrix and the inter-point diffusion operator matrix; assigning a value to an item in the target threshold matrix based on the value of each item in the intermediate matrix; iterating through the nearest neighbor aggregation operator matrix and the inter-point diffusion operator matrix until every item in the target threshold matrix has been assigned a value, obtaining a target threshold matrix with assigned values; and generating an FM halftone screen based on the target threshold matrix with assigned values. This invention improves the efficiency of FM halftone conversion of digital images and solves the problem of low efficiency caused by traditional error diffusion algorithms.

Description

Technical Field

[0001] This invention relates to the field of image hard copy technology, and in particular to a method, apparatus and equipment for generating frequency modulation screens in halftone plate making. Background Technology

[0002] Hard copying of images mainly involves the screen printing technology used in printers and high-end printing plate-making equipment. The screen printing technology used for hard copying images is also known as digital image halftone technology. One common type of digital image halftone technology is frequency-modulated (FM) screen printing. It achieves grayscale reproduction of the original image by controlling the number of colored dots per unit area. Because the colored dots in an FM halftone image are distributed in a non-clustered manner, different gray levels of the original image will correspond to different average distances between colored dots. From a digital image processing perspective, this means the image frequency is changing, hence the name FM screen printing.

[0003] In traditional frequency modulation halftone conversion (FM halftone) methods, error diffusion is the most commonly used approach. However, this method requires complex error diffusion processing for each pixel in the original image, involving various mathematical operations and complex table lookups. In practical applications, the number of pixels in the original image can be in the tens of thousands or even more. Therefore, FM halftone conversion implemented using this traditional error diffusion method results in a significant lag in actual output efficiency, greatly reducing the output speed of the equipment. This hinders efficient batch production in industrial applications and limits its widespread use, necessitating further improvement and refinement. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method, apparatus and equipment for generating frequency modulation halftone in halftone plate making, which can improve the efficiency of frequency modulation halftone conversion of digital images and solve the problem of low efficiency caused by traditional error diffusion algorithms.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A method for generating frequency modulation (FM) screens in halftone screen printing includes:

[0007] Obtain the target threshold matrix, the nearest point aggregation operator matrix, and the inter-point diffusion operator matrix to be assigned values;

[0008] The intermediate matrix is ​​obtained based on the nearest point aggregation operator matrix and the inter-point diffusion operator matrix;

[0009] Based on the value of each data item in the intermediate matrix, a value is assigned to one item in the target threshold matrix;

[0010] The nearest point aggregation operator matrix and the inter-point diffusion operator matrix are iterated until each item in the target threshold matrix is ​​assigned a value, thus obtaining the assigned target threshold matrix; wherein, each item in the assigned target threshold matrix represents the gray level of the digital image in the halftone conversion in the halftone plate making process.

[0011] The frequency modulation network is generated based on the assigned target threshold matrix.

[0012] Optionally, the target threshold matrix, the nearest point aggregation operator matrix, and the inter-point diffusion operator matrix to be assigned values ​​are obtained, including:

[0013] Obtain a target threshold matrix of size W*W, a neighbor aggregation operator matrix with random initialization, and a point diffusion operator matrix with preset initialization values, where W is a positive integer.

[0014] Optionally, based on the nearest-neighbor aggregation operator matrix and the inter-point diffusion operator matrix, an intermediate matrix is ​​obtained, including:

[0015] The nearest point aggregation operator matrix and the inter-point diffusion operator matrix are convolved to obtain an intermediate matrix; the size of the intermediate matrix is ​​equal to that of the target threshold matrix.

[0016] Optionally, assigning a value to an item in the target threshold matrix based on the magnitude of the value of each data item in the intermediate matrix includes:

[0017] Based on the value of each data item in the intermediate matrix, determine the data item with the largest value in the intermediate matrix;

[0018] Based on the index coordinate value of the data with the largest value, assign a value to the item corresponding to the index coordinate value in the target threshold matrix.

[0019] Optionally, the nearest point aggregation operator matrix and the inter-point diffusion operator matrix are iterated until each item in the target threshold matrix is ​​assigned a value, resulting in the assigned target threshold matrix, including:

[0020] The nearest point aggregation operator matrix and the inter-point diffusion operator matrix are iterated to obtain the iterated nearest point aggregation operator matrix and the inter-point diffusion operator matrix;

[0021] Based on the iterated nearest neighbor aggregation operator matrix and the inter-point diffusion operator matrix, a new intermediate matrix is ​​obtained;

[0022] Based on the value of each data item in the new intermediate matrix, assign a value to one item in the target threshold matrix;

[0023] Repeatedly iterate the nearest point aggregation operator matrix and the inter-point diffusion operator matrix until each item in the target threshold matrix is ​​assigned a value, thus obtaining the assigned target threshold matrix.

[0024] Optionally, the nearest point aggregation operator matrix and the inter-point diffusion operator matrix are iterated to obtain the iterated nearest point aggregation operator matrix and the inter-point diffusion operator matrix, including:

[0025] Multiply the nearest point aggregation operator matrix by a preset function to obtain the iterated nearest point aggregation operator matrix;

[0026] Subtract a preset value from the inter-point diffusion operator matrix to obtain the iterated inter-point diffusion operator matrix.

[0027] Optionally, assigning a value to an item in the target threshold matrix based on the magnitude of the value of each data item in the new intermediate matrix includes:

[0028] Based on the value of each data item in the new intermediate matrix, determine the data item with the largest value in the new intermediate matrix;

[0029] Based on the index coordinate value of the data with the largest value, a value is assigned to the item corresponding to the index coordinate value in the target threshold matrix; each time the intermediate matrix is ​​updated, the value assigned in the target threshold matrix is ​​incremented by one.

[0030] The present invention also provides an apparatus for generating frequency modulation screens in screen printing, comprising:

[0031] The acquisition module is used to acquire the target threshold matrix, the nearest point aggregation operator matrix, and the inter-point diffusion operator matrix to be assigned values;

[0032] The processing module is used to obtain an intermediate matrix based on the nearest-point aggregation operator matrix and the inter-point diffusion operator matrix; assign a value to an item in the target threshold matrix based on the value of each item in the intermediate matrix; iterate the nearest-point aggregation operator matrix and the inter-point diffusion operator matrix until each item in the target threshold matrix has been assigned a value, thereby obtaining the assigned target threshold matrix; wherein each item in the assigned target threshold matrix represents the grayscale level for frequency-modulated halftone conversion of the digital image in the halftone plate making process; and generate the frequency-modulated halftone based on the assigned target threshold matrix.

[0033] The present invention also provides a computing device, comprising: a processor and a memory storing a computer program, wherein the computer program, when executed by the processor, performs the method described above.

[0034] The present invention also provides a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the method described above.

[0035] The above-described solution of the present invention has at least the following beneficial effects:

[0036] The above-described solution of the present invention obtains a target threshold matrix, a nearest-neighbor aggregation operator matrix, and an inter-point diffusion operator matrix to be assigned values; obtains an intermediate matrix based on the nearest-neighbor aggregation operator matrix and the inter-point diffusion operator matrix; assigns a value to an item in the target threshold matrix according to the value of each item in the intermediate matrix; iterates the nearest-neighbor aggregation operator matrix and the inter-point diffusion operator matrix until each item in the target threshold matrix is ​​assigned a value, resulting in an assigned target threshold matrix; wherein each item in the assigned target threshold matrix represents the grayscale level for frequency-modulated halftone conversion of a digital image in halftone printing; and generates the frequency-modulated halftone based on the assigned target threshold matrix. This can improve the efficiency of frequency-modulated halftone conversion of digital images and solve the problem of low efficiency caused by traditional error diffusion algorithms. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the first process of the frequency modulation screen generation method in the screen printing process of this invention.

[0038] Figure 2 This is a schematic diagram of the second process of the frequency modulation screen generation method in the screen printing process of this invention.

[0039] Figure 3 This is a schematic diagram of the convolution of the aggregation operator matrix and the diffusion operator matrix in an embodiment of the present invention;

[0040] Figure 4 This is a model diagram of the aggregation operator matrix iterative calculation function according to an embodiment of the present invention;

[0041] Figure 5 This is a schematic diagram of the target threshold matrix in an embodiment of the present invention;

[0042] Figure 6 This is a schematic diagram of the first halftone dot of a frequency-modulated halftone image according to an embodiment of the present invention;

[0043] Figure 7 This is a schematic diagram of the second halftone dot of a frequency-modulated halftone image according to an embodiment of the present invention;

[0044] Figure 8 This is a structural diagram of the frequency modulation screen generation device in the screen printing process of this invention. Detailed Implementation

[0045] Exemplary embodiments of the invention will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0046] like Figure 1 As shown, an embodiment of the present invention proposes a method for generating a frequency modulation (FM) mesh in screen printing, comprising:

[0047] Step 11: Obtain the target threshold matrix, the nearest point aggregation operator matrix, and the inter-point diffusion operator matrix to be assigned values;

[0048] Here, the target threshold matrix to be assigned values ​​is an empty matrix with a defined target size, and each item in this empty target threshold matrix can be further assigned values ​​according to a certain order and rules. The assigned target threshold matrix can be used to perform frequency-modulated halftone image conversion on digital images in halftone printing, that is, to perform frequency-modulated halftone printing on digital images to obtain frequency-modulated halftone images. Halftone images are relative to continuous images, such as printed images in halftone printing. They express image levels and color changes through the size or density of halftone dots. From a microscopic perspective, the detail changes of such images are discontinuous, hence the name halftone image. Halftone dots refer to clusters of dyed areas formed by the geometrical aggregation of two adjacent dyed dots.

[0049] The nearest point aggregation operator matrix and the inter-point diffusion operator matrix are two attribute operator matrices. In this application, the nearest point aggregation operator matrix is ​​denoted as U1, and the inter-point diffusion operator matrix is ​​denoted as U2.

[0050] Step 12: Obtain the intermediate matrix based on the nearest point aggregation operator matrix and the inter-point diffusion operator matrix;

[0051] Step 13: Assign a value to one item in the target threshold matrix based on the value of each item in the intermediate matrix;

[0052] Here, one item in the target threshold matrix refers to, for example... Figure 5 The number in one of the squares of the matrix shown.

[0053] Step 14: Iterate the nearest point aggregation operator matrix and the inter-point diffusion operator matrix until each item in the target threshold matrix is ​​assigned a value, thus obtaining the assigned target threshold matrix; wherein, each item in the assigned target threshold matrix represents the gray level of the digital image in the halftone conversion in the halftone printing process.

[0054] Here, assigning a value to each item in the target threshold matrix means as follows: Figure 5 Each square in the matrix shown has a corresponding value. In... Figure 5 In the target threshold matrix shown, each number represents a gray level, and each gray level is determined by a series of parameters such as halftone dot distribution, dot size, and arrangement. By determining the gray levels of the halftone image, the dot distribution, dot size, and arrangement can be controlled according to those gray levels, thereby achieving the conversion from a digital image to a halftone image.

[0055] Step 15: Generate the frequency modulation network based on the assigned target threshold matrix.

[0056] In this embodiment, as Figure 2 As shown, this paper describes a matrix-based method for generating frequency modulation (FM) halftone screens. Building upon the principle of halftone amplitude modulation (AM) halftone screening based on a threshold matrix approach, it fully utilizes the fundamental implementation method of threshold matrices. Simultaneously, it combines random distribution modulation of error diffusion with algorithms for AM halftone dot aggregation. Within a fixed-size matrix region, it achieves discrete dot distribution while effectively aggregating some dots as the threshold increases, better meeting the output requirements of printing processes. Furthermore, while ensuring the simulated random dot distribution effect of error diffusion, it employs a lookup table mechanism, thus significantly improving the efficiency of FM halftone screening and resolving the inefficiency problem caused by traditional error diffusion algorithms. This fully meets the efficiency standards for normal industrial applications.

[0057] In an optional embodiment of the present invention, step 11 may include:

[0058] Step 111: Obtain a target threshold matrix of size W*W, a neighbor aggregation operator matrix with random initialization, and a point diffusion operator matrix with preset initialization, where W is a positive integer.

[0059] In this embodiment, the target threshold matrix is ​​a square with a side length of W. Let the target threshold matrix be M. Then, an initial zero value is assigned to each item in matrix M. The value of each item in the target threshold matrix M after assignment determines the order in which the value is "lit up," and this order is represented by integers from largest to smallest. The value range of each item is M[x,y]∈[1,WxW]. Initializing to zero marks it as unassigned. Here, x and y represent the column and row indices of the target threshold matrix, respectively.

[0060] Each item in the nearest neighbor aggregation operator matrix U1 is initialized with a unique pseudo-random number, whose value range is U1[x,y]∈(0,1). In this application, a possible implementation of the nearest neighbor aggregation operator matrix U1 is as follows:

[0061] U1=(a×x+b×y)mod(c)÷255

[0062] Where x and y represent the horizontal and vertical coordinates of each value in matrix U1, and a, b, and c are three positive integers that are coprime, and their values ​​must be guaranteed to be (a, b, c) ∈ [0, 255].

[0063] Each item in the inter-point diffusion operator matrix U2 is initialized with a preset value, preferably 1.0. In subsequent iterative calculations, the value range of matrix U2 is U2[x,y]∈[1,AxA], where A is the side length of the square matrix U2 and A is a positive integer.

[0064] In an optional embodiment of the present invention, step 12 may include:

[0065] Step 121: Perform matrix convolution on the nearest point aggregation operator matrix and the inter-point diffusion operator matrix to obtain an intermediate matrix; the intermediate matrix is ​​equal in size to the target threshold matrix.

[0066] In this embodiment, there is no limitation on the size of the nearest-neighbor aggregation operator matrix and the inter-point diffusion operator matrix. For example... Figure 3 As shown, the 3*3 matrix is ​​the inter-point diffusion operator matrix, and the 10*10 matrix is ​​the neighbor aggregation operator matrix. By controlling the stride and padding value of the convolution, an intermediate matrix of the same size as the target threshold matrix is ​​obtained.

[0067] In an optional embodiment of the present invention, step 13 may include:

[0068] Step 131: Based on the value of each data item in the intermediate matrix, determine the data item with the largest value in the intermediate matrix;

[0069] Step 132: Assign a value to the item corresponding to the index coordinate value of the data with the largest value in the target threshold matrix.

[0070] In this embodiment, the size of each data item in the intermediate matrix U3 is counted, and the maximum value U3[x] is found. max y max This value corresponds to the index coordinate [x] max y max The index coordinates [x] in the target threshold matrix M. max y maxThe corresponding position term is assigned the integer C. When the intermediate matrix is ​​obtained for the first time after initializing the nearest point aggregation operator matrix and the inter-point diffusion operator matrix, the term corresponding to the maximum value coordinate in the target threshold matrix M is assigned the value 1, that is, C is 1 at this time. During the iteration of the nearest point aggregation operator matrix and the inter-point diffusion operator matrix, the value of the corresponding term in the target threshold matrix M is increased by 1 with each iteration.

[0071] In an optional embodiment of the present invention, step 14 may include:

[0072] Step 141: Iterate the nearest point aggregation operator matrix and the inter-point diffusion operator matrix to obtain the iterated nearest point aggregation operator matrix and the inter-point diffusion operator matrix;

[0073] Step 142: Based on the iterated nearest neighbor aggregation operator matrix and the inter-point diffusion operator matrix, a new intermediate matrix is ​​obtained;

[0074] Step 143: Assign a value to one item in the target threshold matrix based on the value of each item in the new intermediate matrix;

[0075] Step 144: Repeat the iteration of the nearest point aggregation operator matrix and the inter-point diffusion operator matrix until each item in the target threshold matrix is ​​assigned a value, thus obtaining the assigned target threshold matrix.

[0076] In this embodiment, each iteration of the nearest-neighbor aggregation operator matrix and the inter-point diffusion operator matrix assigns a value to one item in the target threshold matrix. Since each item in the W*W target threshold matrix is ​​assigned a value, it requires W*W-1 iterations. During each iteration, the assigned item in the target threshold matrix is ​​determined based on the coordinates of the maximum value in the intermediate matrix, ensuring that each item in the target threshold matrix is ​​assigned a value at intervals, ultimately resulting in the complete target threshold matrix.

[0077] In an optional embodiment of the present invention, step 141 may include:

[0078] Step 1411: Multiply the nearest point aggregation operator matrix with a preset function to obtain the iterated nearest point aggregation operator matrix;

[0079] Step 1412: Subtract a preset value from the inter-point diffusion operator matrix to obtain the iterated inter-point diffusion operator matrix.

[0080] In this embodiment, the iteration method of the nearest point aggregation operator matrix adopts the following formula:

[0081] U1[x,y] = U1[x,y] × F(d)

[0082] Where [x,y] represents the index coordinates of each entry in the U1 matrix, and the F(d) function equation follows the ringing effect law, consisting of a combination of multiple linear equations. Its variation follows a pattern where the initial amplitude is large, and as the density of the distribution points changes, the amplitude at a single point gradually tends to a stable value. The F(d) function is as follows:

[0083]

[0084] in, f is the cutoff frequency of a single point in the frequency modulation network, and it is also the reciprocal of the mean of the pairwise distances between the already assigned terms in the target threshold matrix. f can be expressed as f = 1 / ∑r, where r is the distance between the two terms.

[0085] The model diagram of the iterative calculation function of the nearest point aggregation operator matrix is ​​shown below. Figure 4 As shown.

[0086] The iteration method for the inter-point diffusion operator matrix is ​​as follows:

[0087] U2[x,y]=U2[x,y]-h

[0088] The definition of h is as follows:

[0089] h = exp(-r 2 / d 2 ) / ∑exp(-r 2 / d 2 )

[0090] Where r is the average distance between the two items,

[0091] In an optional embodiment of the present invention, step 143 may include:

[0092] Step 1431: Based on the value of each data item in the new intermediate matrix, determine the data item with the largest value in the new intermediate matrix;

[0093] Step 1432: Assign a value to the item corresponding to the index coordinate value of the data with the largest value in the target threshold matrix; each time the intermediate matrix is ​​updated, the value assigned in the target threshold matrix is ​​incremented by one.

[0094] In this embodiment, the intermediate matrix iterates continuously, and each item in the target threshold matrix is ​​gradually assigned a value. It should be noted that in this application, each item in the target threshold matrix is ​​assigned a value in the order they are assigned, with the value increasing by 1 each time. For example, in one iteration, the item with index coordinates [3,2] is assigned the value 5; after the next iteration, the index coordinates of the maximum value in the intermediate matrix are [5,8], so the item in the target threshold matrix with coordinates [5,8] is assigned the value 6; in the next iteration, the corresponding item is assigned the value 7, and so on. A partial view of the final target threshold matrix after assignment is shown below. Figure 5 As shown, the integers are arranged at intervals, and each item is assigned a value.

[0095] As mentioned earlier, each item in the target threshold matrix represents a gray level, and the dot effect of the generated halftone image is controlled according to this gray level. Figure 6 and Figure 7 The image shown illustrates the halftone dot effect generated at different gray levels of the target threshold matrix. Figure 7 The grayscale level is higher than Figure 6 The grayscale levels.

[0096] The present invention will be further described below with reference to embodiments:

[0097] Example 1,

[0098] Step 1: Set the target threshold matrix M, which contains a series of numerical arrays including halftone dot distribution, dot size, and arrangement. The matrix is ​​square with a side length of 128. Assign an initial zero value to each item in matrix M. The value of each item in matrix M depends on the order in which it is "lit up," represented by integers from largest to smallest. The value range for each item is M[x,y]∈[1,128x128]. Initializing to zero marks it as unassigned. Here, x and y represent the column and row indices of the matrix, respectively.

[0099] Step 2: Define two attribute operator matrices U1 and U2 of the same size as the M matrix. Operator matrix U1 is the nearest neighbor aggregation operator matrix, and U2 is the inter-point diffusion operator matrix. Initialize each item U1[x,y] in matrix U1 with a unique pseudo-random number.

[0100] U1[x,y]=(a×x+b×y)mod(c)÷255

[0101] Where: x and y represent the horizontal and vertical coordinates of each value in matrix U1, and a, b, and c are three positive integers that are coprime. In this embodiment, the parameters a, b, and c are calculated using the following formulas:

[0102] Tr n=Tr n-1 +Tr n-2 +Tr n-3 (For n>2)

[0103] Where: Tr0 = 0, Tr1 = 1, Tr2 = 1. Calculate the values ​​of Tr3, Tr4, and Tr5 as parameters a, b, and c respectively. The range of values ​​is U1[x,y]∈(0,1).

[0104] At the same time, each item U2[x,y] in the U2 matrix is ​​initialized with a value of 1.0.

[0105] Step 3: Perform matrix convolution on attribute operator matrices U1 and U2 to obtain the intermediate matrix U3. The calculation process is as follows: in: This represents a convolution operation. Calculate the value of each data item in U3 and find the maximum value U3[x]. max y max The index coordinates [x] corresponding to this value max y max In matrix M, the positional item is assigned the integer C, which is an incrementing item with a value range of [1, W x W]. After each assignment to M, C is incremented by 1.

[0106] Step 4: Iteratively calculate the values ​​of each item in the operator matrix U1.

[0107] Step 5: Iterate through the values ​​of each item in the operator matrix U2.

[0108] Step Six: Repeat steps three through five until all points in M ​​are "lit up" in sequence and assigned values ​​sequentially from 1 to W×W.

[0109] The method described in this invention, based on a threshold matrix lookup table-based halftone screening algorithm, fully leverages the characteristics of multi-bit imaging devices by considering the image quality requirements of the device. Compared to traditional multi-level grayscale error diffusion frequency modulation (FM) screening algorithms, it significantly improves the efficiency of FM screening while maintaining the tonal quality of multi-level grayscale levels. Using the method described in this invention, FM screening output can be completed efficiently on multi-bit deep output devices without sacrificing quality.

[0110] like Figure 8 As shown, the present invention also provides a frequency modulation screen generation device 80 for screen printing, comprising:

[0111] The acquisition module 81 is used to acquire the target threshold matrix, the nearest point aggregation operator matrix, and the inter-point diffusion operator matrix to be assigned values;

[0112] Processing module 82 is used to obtain an intermediate matrix based on the nearest point aggregation operator matrix and the inter-point diffusion operator matrix; assign a value to an item in the target threshold matrix based on the value of each item in the intermediate matrix; iterate the nearest point aggregation operator matrix and the inter-point diffusion operator matrix until each item in the target threshold matrix is ​​assigned a value, thereby obtaining the assigned target threshold matrix; wherein each item in the assigned target threshold matrix represents the grayscale level for frequency modulation halftone conversion of the digital image in the halftone plate making process; and generate the frequency modulation halftone based on the assigned target threshold matrix.

[0113] Optionally, the target threshold matrix, the nearest point aggregation operator matrix, and the inter-point diffusion operator matrix to be assigned values ​​are obtained, including:

[0114] Obtain a target threshold matrix of size W*W, a neighbor aggregation operator matrix with random initialization, and a point diffusion operator matrix with preset initialization values, where W is a positive integer.

[0115] Optionally, based on the nearest-neighbor aggregation operator matrix and the inter-point diffusion operator matrix, an intermediate matrix is ​​obtained, including:

[0116] The nearest point aggregation operator matrix and the inter-point diffusion operator matrix are convolved to obtain an intermediate matrix; the size of the intermediate matrix is ​​equal to that of the target threshold matrix.

[0117] Optionally, assigning a value to an item in the target threshold matrix based on the magnitude of the value of each data item in the intermediate matrix includes:

[0118] Based on the value of each data item in the intermediate matrix, determine the data item with the largest value in the intermediate matrix;

[0119] Based on the index coordinate value of the data with the largest value, assign a value to the item corresponding to the index coordinate value in the target threshold matrix.

[0120] Optionally, the nearest point aggregation operator matrix and the inter-point diffusion operator matrix are iterated until each item in the target threshold matrix is ​​assigned a value, resulting in the assigned target threshold matrix, including:

[0121] The nearest point aggregation operator matrix and the inter-point diffusion operator matrix are iterated to obtain the iterated nearest point aggregation operator matrix and the inter-point diffusion operator matrix;

[0122] Based on the iterated nearest neighbor aggregation operator matrix and the inter-point diffusion operator matrix, a new intermediate matrix is ​​obtained;

[0123] Based on the value of each data item in the new intermediate matrix, assign a value to one item in the target threshold matrix;

[0124] Repeatedly iterate the nearest point aggregation operator matrix and the inter-point diffusion operator matrix until each item in the target threshold matrix is ​​assigned a value, thus obtaining the assigned target threshold matrix.

[0125] Optionally, the nearest point aggregation operator matrix and the inter-point diffusion operator matrix are iterated to obtain the iterated nearest point aggregation operator matrix and the inter-point diffusion operator matrix, including:

[0126] Multiply the nearest point aggregation operator matrix by a preset function to obtain the iterated nearest point aggregation operator matrix;

[0127] Subtract a preset value from the inter-point diffusion operator matrix to obtain the iterated inter-point diffusion operator matrix.

[0128] Optionally, assigning a value to an item in the target threshold matrix based on the magnitude of the value of each data item in the new intermediate matrix includes:

[0129] Based on the value of each data item in the new intermediate matrix, determine the data item with the largest value in the new intermediate matrix;

[0130] Based on the index coordinate value of the data with the largest value, a value is assigned to the item corresponding to the index coordinate value in the target threshold matrix; each time the intermediate matrix is ​​updated, the value assigned in the target threshold matrix is ​​incremented by one.

[0131] It should be noted that this device is the same as the method described above. All implementations in the above method embodiments are applicable to the embodiments of this device and can achieve the same technical effect.

[0132] Embodiments of the present invention also provide a computing device, including: a processor and a memory storing a computer program, wherein the computer program, when executed by the processor, performs the method as described above. All implementations in the above method embodiments are applicable to this embodiment and can achieve the same technical effects.

[0133] Embodiments of the present invention also provide a computer-readable storage medium storing instructions that, when executed on a computer, cause the computer to perform the method as described above. All implementations in the above method embodiments are applicable to this embodiment and can achieve the same technical effects.

[0134] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0135] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0136] In the embodiments provided by this invention, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0137] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0138] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0139] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, ROM, RAM, magnetic disks, or optical disks.

[0140] Furthermore, it should be noted that in the apparatus and method of the present invention, it is obvious that the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered equivalent solutions of the present invention. Moreover, the steps performing the above-described series of processes can naturally be executed in the order described, but are not necessarily required to be executed in chronological order; some steps can be executed in parallel or independently of each other. Those skilled in the art will understand that all or any step or component of the method and apparatus of the present invention can be implemented in any computing device (including processors, storage media, etc.) or network of computing devices, in hardware, firmware, software, or a combination thereof. This is something that those skilled in the art can achieve by using their basic programming skills after reading the description of the present invention.

[0141] Therefore, the object of the present invention can also be achieved by running a program or a set of programs on any computing device. The computing device can be a known general-purpose device. Therefore, the object of the present invention can also be achieved simply by providing a program product containing program code implementing the method or apparatus. That is, such a program product also constitutes the present invention, and the storage medium storing such a program product also constitutes the present invention. Obviously, the storage medium can be any known storage medium or any storage medium developed in the future. It should also be noted that in the apparatus and method of the present invention, it is obvious that the components or steps can be decomposed and / or recombined. These decompositions and / or recombinations should be considered equivalent to the present invention. Furthermore, the steps performing the above series of processes can naturally be performed in the order described, but are not necessarily required to be performed in chronological order. Some steps can be performed in parallel or independently of each other.

[0142] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for generating a frequency modulation screen in halftone screen printing, characterized in that, include: Obtain the target threshold matrix to be assigned, the nearest point aggregation operator matrix U1, and the inter-point diffusion operator matrix U2; The intermediate matrix is ​​obtained based on the nearest point aggregation operator matrix U1 and the inter-point diffusion operator matrix U2; Based on the value of each data item in the intermediate matrix, a value is assigned to one item in the target threshold matrix; The nearest point aggregation operator matrix U1 and the inter-point diffusion operator matrix U2 are iterated until each item in the target threshold matrix is ​​assigned a value, thus obtaining the assigned target threshold matrix; wherein, each item in the assigned target threshold matrix represents the gray level of the digital image in the halftone conversion in the halftone printing process. The frequency modulation network is generated based on the assigned target threshold matrix; Wherein, the nearest point aggregation operator matrix U1 is: Where x and y represent the horizontal and vertical coordinates of each value in matrix U1, and a, b, and c are three positive integers that are coprime. ; Each item in the inter-point diffusion operator matrix U2 is initialized with a preset value, and the range of values ​​for matrix U2 is as follows: Where A is the side length of the square matrix U2, and A is a positive integer; The process of assigning a value to an item in the target threshold matrix based on the value of each item in the intermediate matrix includes: Based on the value of each data item in the intermediate matrix, determine the data item with the largest value in the intermediate matrix; Based on the index coordinate value of the data with the largest value, assign a value to the item corresponding to the index coordinate value in the target threshold matrix.

2. The method for generating a frequency modulation screen in screen printing according to claim 1, characterized in that, Obtain the target threshold matrix, nearest neighbor aggregation operator matrix, and inter-point diffusion operator matrix to be assigned values, including: Get W A target threshold matrix of size W, a nearest neighbor aggregation operator matrix with random initialization, and a point diffusion operator matrix with preset initialization values, where W is a positive integer.

3. The method for generating a frequency modulation screen in screen printing according to claim 1, characterized in that, Based on the nearest-neighbor aggregation operator matrix and the inter-point diffusion operator matrix, an intermediate matrix is ​​obtained, including: The nearest point aggregation operator matrix and the inter-point diffusion operator matrix are convolved to obtain an intermediate matrix; the size of the intermediate matrix is ​​equal to that of the target threshold matrix.

4. The method for generating a frequency modulation screen in screen printing according to claim 1, characterized in that, The nearest neighbor aggregation operator matrix and the inter-point diffusion operator matrix are iterated until each item in the target threshold matrix is ​​assigned a value, resulting in the assigned target threshold matrix, including: The nearest point aggregation operator matrix and the inter-point diffusion operator matrix are iterated to obtain the iterated nearest point aggregation operator matrix and the inter-point diffusion operator matrix; Based on the iterated nearest neighbor aggregation operator matrix and the inter-point diffusion operator matrix, a new intermediate matrix is ​​obtained; Based on the value of each data item in the new intermediate matrix, assign a value to one item in the target threshold matrix; Repeatedly iterate the nearest point aggregation operator matrix and the inter-point diffusion operator matrix until each item in the target threshold matrix is ​​assigned a value, thus obtaining the assigned target threshold matrix.

5. The method for generating a frequency modulation screen in screen printing according to claim 4, characterized in that, Iterating through the nearest-neighbor aggregation operator matrix and the inter-point diffusion operator matrix yields the iterated nearest-neighbor aggregation operator matrix and the inter-point diffusion operator matrix, including: Multiply the nearest point aggregation operator matrix by a preset function to obtain the iterated nearest point aggregation operator matrix; Subtract a preset value from the inter-point diffusion operator matrix to obtain the iterated inter-point diffusion operator matrix.

6. The method for generating a frequency modulation screen in screen printing according to claim 4, characterized in that, Assigning a value to an item in the target threshold matrix based on the value of each data item in the new intermediate matrix includes: Based on the value of each data item in the new intermediate matrix, determine the data item with the largest value in the new intermediate matrix; Based on the index coordinate value of the data with the largest value, a value is assigned to the item corresponding to the index coordinate value in the target threshold matrix; each time the intermediate matrix is ​​updated, the value assigned in the target threshold matrix is ​​incremented by one.

7. A frequency modulation screen generation device for screen printing, characterized in that, include: The acquisition module is used to acquire the target threshold matrix to be assigned, the nearest point aggregation operator matrix U1, and the inter-point diffusion operator matrix U2; The processing module is used to obtain an intermediate matrix based on the nearest-neighbor aggregation operator matrix U1 and the inter-point diffusion operator matrix U2; assign a value to an item in the target threshold matrix based on the value of each item in the intermediate matrix; iterate the nearest-neighbor aggregation operator matrix U1 and the inter-point diffusion operator matrix U2 until each item in the target threshold matrix has been assigned a value, thereby obtaining the assigned target threshold matrix; wherein each item in the assigned target threshold matrix represents the grayscale level for frequency-modulated halftone conversion of the digital image in the halftone plate making process; and generate the frequency-modulated halftone based on the assigned target threshold matrix. Wherein, the nearest point aggregation operator matrix U1 is: Where x and y represent the horizontal and vertical coordinates of each value in matrix U1, and a, b, and c are three positive integers that are coprime. ; Each item in the inter-point diffusion operator matrix U2 is initialized with a preset value, and the range of values ​​for matrix U2 is as follows: Where A is the side length of the square matrix U2, and A is a positive integer; The process of assigning a value to an item in the target threshold matrix based on the value of each item in the intermediate matrix includes: Based on the value of each data item in the intermediate matrix, determine the data item with the largest value in the intermediate matrix; Based on the index coordinate value of the data with the largest value, assign a value to the item corresponding to the index coordinate value in the target threshold matrix.

8. A computing device, characterized in that, include: A processor, a memory storing a computer program, wherein the computer program, when executed by the processor, performs the method as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, A storage instruction that, when executed on a computer, causes the computer to perform the method as described in any one of claims 1 to 6.

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