The Study Of3d-DCT And Compression Algorithm For Color Halftone Images

Halftone image, as special bi-level image, is widely used in binary output fieldsuch as facsimile and printing.Most compression algorithms are focused on grayhalftone image at present. If these algorithms are directly used in sub-channel of colorhalftone image, inter-channel correlation is neglected. Much redundant information,limited compression rate, and narrow range are the usual questions in the only existingcompression algorithms for color halftone image.In view of the questions mentioned above, color halftone image is processed as awhole based on the orthogonality of three dimensional discrete cosine transform,which results in eliminating the spatial redundancy and color inter-channelredundancy at the same time.By making further research on three dimensional discretecosine transform and analyzing energy distribution characteristics of color halftoneimage transformed, a statistical method of energy distribution characteristics based onprobability is proposed, then a compression algorithm for color halftone image ispresented. The experimental results show that new algorithm is reasonable andeffective.