Rational tangent amplitude modulation screening method based on minimum threshold matrix

Abstract

The invention relates to a rational tangent amplitude modulation screening method based on a minimum threshold matrix. On the basis of a minimum threshold matrix design principle, an amplitude modulation screening algorithm angle and a threshold matrix are designed, and the method comprises the following steps of: 1, designing the sizes of 0-degree, 15-degree, 45-degree and 75-degree threshold matrixes respectively according to the design principle of the minimum threshold matrix; 2, after the sizes of different screening angle threshold matrixes are designed, designing the screening thresholdmatrixes of 0 degree, 15 degrees, 45 degrees and 75 degrees by taking the angular points of the grids as starting points according to a threshold matrix design rule; 3, screening the whole grayscaleimage; and step 4, solving pixel coordinates of the original grayscale image. According to the method, screening including 0-degree screening, 15-degree screening, 45-degree screening and 75-degree screening is achieved at different angles, rational tangent screening cannot be achieved for 15-degree screening and 75-degree screening, an approximate angle screening mode is adopted, an error is reduced to the minimum, and influence of the angle error on a screened image is reduced to the minimum.

Description

technical field [0001] The invention belongs to the technical field of image reproduction, and relates to a digital halftone image processing algorithm, in particular to a rational tangent amplitude modulation screening method based on a minimum threshold matrix. Background technique [0002] The model of the amplitude modulation screening algorithm is the method of gathering and orderly dithering of recording points, and the more accurate name of gathering and orderly dithering of recording points is pulse surface area modulation PSAM, which means that the pixel value of the continuous tone image input by the screening processing system is mapped to a proportional In the unit formed by the distribution of black pixels and white pixels of the original gray value of the pixel, the dots with different area ratios are generated. Due to the importance of dots to image reproduction, how to simulate traditional dots in digital processing has become one of the main tasks of digital...

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Problems solved by technology

When the angle of the grid line is 0° and 45°, this requirement is easy to realize, but when the angle of the line line is 15° or 75°, because the tangent value is an irrational number, it cannot guarantee that the corner point of the grid is consistent with the grid recorded by the output device. The corners overlap, so it becomes a technical problem for AM digital screening

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