Digital image halftone method based on small-wavelet-domain multi-scale information fusion

Abstract

The invention relates to a digital image halftone method based on small-wavelet-domain multi-scale information fusion and belongs to the technical field of digital image processing before printing. The digital image halftone method based on small-wavelet-domain multi-scale information fusion comprises the steps that a continuous-tone image is converted into a grayscale image, and whether the grayscale image is a standard 2n*2n grayscale image is judged; small-wavelet-domain four-scale information of the standard grayscale image is obtained through two-dimension discrete wavelet transformation, and an edge error measure function is obtained by means of wavelet detail coefficient relation between autocorrelation fusion layers of inter-scale wavelet coefficients; the standard grayscale image is divided into k areas with the K-means cluster method, and an area error measure function is established with the reciprocals of variances of the areas serving as weights; a mixed error measure function is established according to the additivity of the edge error measure function and the area error measure function, and then errors of the standard grayscale image and a rough halftone image are minimized with the direct binary searching method. The digital image halftone method based on small-wavelet-domain multi-scale information fusion solves the problem that according to an existing method, the smoothness and the definition of images can not be guaranteed at the same time.

Description

technical field [0001] The invention relates to a digital image halftone method based on wavelet domain multi-scale information fusion, and belongs to the technical field of digital image prepress processing. Background technique [0002] The engraving method of laser gravure plate making is a scanning engraving method that imitates the printing output device. The output method of laser engraving gravure is to control the switching state of the laser, so that the high-energy laser beam is irradiated on a specific point on the surface of the workpiece, so that the point is quickly evaporated, and a concave point is formed on the surface of the workpiece, thus showing two tones of black and white . Therefore, for multi-gray images, it must be converted into a black and white binary image suitable for laser output through digital halftone technology before output. In addition to factors such as laser wavelength, pulse frequency, laser beam quality, and processing material cha...

AI Technical Summary

Problems solved by technology

Existing halftone methods model images from a single scale. Although they have been successfully applied to a certain extent in static environments, the quality of halftone images in dynamic environments is not ideal.

The reason is that the fine-scale information is very unreliable in a dynamic environment, so that the spatial and frequency adaptive error measurement information in a single scale has strong dynamic randomness

Due to the attention mechanism of the human visual system, people can observe images at different resolutions, and then evaluate the image quality, but affected by external factors such as illumination changes, shadows, background noise, etc. Image information has strong dynamic randomness in time and space

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