Patent ID: 6606415
Filing Date: 2003-08-12
Classification: G06T

Abstract:
A method for adaptively controlling the compression of a bitmap image to guarantee the attainment of a predetermined compression ratio comprising the steps of:partitioning said bitmap image into blocks; classifying each block according to image content; compressing each block by an algorithm selected to be most efficient for the class of the block; during compression, comparing the actual attained compression ratio to the target compression ratio and generating an error signal if the target compression ratio has not been attained, where this comparing may be done on a block, row of blocks or page basis and the resultant error signal is used to adjust the compression ratio for subsequent blocks; and adjusting the compression ratio by changing a block classification threshold in response to said error signal, where compression is increased by shifting the block classification threshold to increase the number of blocks classified as SOLID, and is decreased by increasing the number of blocks classified as IMAGE.