2 results about "JPEG" patented technology

The invention discloses a hybrid image compressing method based on block classification. In the invention, blocks are divided into text/ image block, natural image block and hybrid block according to different features of text/image area and natural image area of original images in the aspect of color and texture; then a compression mode in which palette coding, Hextile coding and LZW coding are combined is used in the text/ image block, a JPEG lossy compression mode is used in the natural image while the algorithm of the combination of the two modes is used in the hybrid block. The invention has the advantages that based on the block classification method, the text/image area and the natural image area can be divided up accurately, and that the blocks are respectively encoded can keep rather acuminate edge of the text/image block so as to enhance visual effect on the basis of ensuring higher compression efficiency and upgrade the peak signal to noise ratio of reconstructed images; the complexity of the algorithm is lower.

Forensic method for identifying forged documents. For each of a stream of incoming jpeg images, using a processor configured for determining whether jpeg image/s is a replacement forgery by determining whether a first portion of individual image which resides at a known location (known likely to be replaced by forger) within the individual jpeg image has been replaced, including: indicator, face-djpg, for the first portion at known location; computing indicator, aka nonface-djpg, for a second portion of individual image which resides at a comparison location within the jpeg image known as unlikely to be replaced by a forger; and determining whether face-djpg and nonface-djpg fulfill predetermined logical criterion and deciding whether the individual jpeg image is a replacement forgery accordingly.