Patent ID: 7362474
Filing Date: 2008-04-22
Classification: H04N

Abstract:
1. A printing quality enhancement via graphic/text detection method in compression (JPEG) image, wherein an unit of n×n pixels of plural compressed subimages of a compressed image is taken as a minimum feature extraction unit, and the subimages are taken as input unit, then an output unit is formed via a feature attribute and non-feature attribute processing, and finally the output unit is printed, such a method includes the following steps: subimage decompression serving to transform the compressed subimage pixels from frequency domain into space domain, including a DCT; GTD analysis serving to determine the attribute of the subimages by calculating detail features of the subimages based on the frequency parameter of DCT of the subimages; weight adjustment serving to process the respective subimages that have been processed by the GTD analysis in a manner that respectively processes, based on different weight processing, the subimages having feature attribute and the subimages having non-feature attribute, and result of the weight processing is used to determine edge direction of the respective subimages; output processing serving to smoothly distribute ink dots of the respective subimages of non-edge feature and to sharply distribute ink dots of the subimages of edge feature with halftoning error diffusion.