Abstract:

The halftone algorithm is one of the key technologies for image printing. Introduced a series of halftone algorithms such as the thresholding value comparing algorithm，halftone algorithm with random thresholding values, error diffusion algorithm, dot diffusion algorithm, ordered dithering and dithering algorithm. Commercial raster image processor usually uses dithering algorithm for halftone speed. The quality of halftone image produced by dithering algorithm depends on dithering matrix. The geometry based method to design dithering matrix can optimize the halftone image quality while maintain the constraint of stack. The halftone algorithm with random thresholding values can eliminate the moiré of image. The foundation of random halftone algorithms is to distribute a number of points in a square area randomly and uniformly. Asano proposed a proposition that problem of distributing random points and circle packing in a square area are equal. This paper gives a basic proof to this proposition. Finally, a few topics regarding the tobeinvestigated image halftone are proposed.

Key words: halftone；blue noise model；pseudo random distribution；geometry subdivision;dithering matrix