Patent ID: 6337747
Filing Date: 2002-01-08
Classification: G06K,G06T,H04N

Abstract:
A method for compressing raster image data comprised of M (M>1) bands to a compression ratio of at least Câ€²:1, each band being comprised of a plurality of pixels each having a pixel value, the method comprising:a first compressing step of compressing N (1&lE;Ncalculating a compression ratio for the compressed N bands of raster image data; a first determining step of determining whether the calculated compression ratio is at least Câ€²:1, wherein Câ€² is less than C; and a second compressing step of compressing a remaining (Mâˆ’N) bands of the raster image data using the lossless compression technique if it is determined that the calculated compression ratio is at least Câ€²:1, wherein the remaining bands are rendered after the first compressing step and each band of raster image data is compressed before rendering a next band, and wherein, if it is determined in said first determining step that the calculated compression ratio is less than the Câ€²:1, the raster image data is compressed to a compression ratio of at least C:1 using a lossy compression technique.