Patent ID: 6343152
Filing Date: 2002-01-29
Classification: H04N

Abstract:
A method for encoding a bi-level image which has been created from a gray scale image to enable a resulting image to be printed by a continuous scan raster device having a memory insufficient to store the bi-level image comprising the steps of:a) compressing the bi-level image by: 1) dividing said bi-level image into n-by-m bit blocks where n and m are predetermined values, each of said n-by-m bit blocks having a gray scale content which varies as a function of a number of bits having a 0 value and a number of bits having a 1 value in each of said blocks; 2) determining for each of a predetermined number of said blocks a value representing said gray scale content, each said determined value requiring less storage than required by its corresponding block; 3) storing compressed portions using said determined values in a memory; b) passing the determined values stored in said memory to a decompressor, said decompressor decompressing the compressed portions at a processing speed required by said continuous scan raster device; c) repeating said steps a)(2) to b) until said bi-level image has been compressed in its entirety and decompressed to form said resulting image for printing by said continuous scan raster device.