Research Of Halftone Image Compression

The technique for halftone compression is great valuable in applications of fax in the bi-level image, document management systems, etc. This paper does much research on the status quo of halftone compression at home and abroad, introduces the international standard for compression of bi-level images and bi-level documents- JBIG2, and concludes the characteristics of halftone by analyzing the generation and classification of halftone image. Based on the studying the algorithms available for image compression, an algorithms based JBIG2 for halftone image compression is proposed in the paper, and it is also showed post processing the decoder may apply to increase the quality further. It is noticeable that the coding method has some loss in introducing artifacts in the reconstructed image. Experiments show that the coding method constitutes an effective coding for periodic halftones image, when the period is complete and integer, the coding method can provide perceptually lossless coding, and for stochastic halftones, the coding method provides a significant compression rate compared to lossless coding. Furthermore, the algorithm can improve the image quality by reducing or avoiding artificial texture.