Black block skipping lossless compression algorithm for dither halftone image
抖动半调图像跳黑块无损压缩算法

This paper presented a black block skipping lossless compression method for ordered dither halftone image. With the characteristics analysis of dither halftone image, it designed the preprocessor for halftone image which was consisted by sub-blocks and XOR calculation. After the pretreatment, it converted halftone image into binary image where isolated white pixel surrounded by large area of black pixels, then compressed binary image by black block skipping coding. In the black block skipping coding, used the specific short code word in only a white pixel of non-black block, and used direct coding in the remaining types of non-black block. The experimental results show that improved black block skipping coding can get effective compression for non-black block in a certain extent. In addition, the new algorithm can get good compression efficiency, time and space complexity of algorithm is low.