Method and apparatus for increasing compressibility of multibit image data with the LSB value determined in the thresholding operation based on pixel position

摘要

A method and apparatus for processing image data of pixels to be rendered for efficient storage in a memory or efficient transmission wherein a grey level value of a rendered pixel is represented by multiple bits including a most significant bit (MSB) and a least significant bit (LSB). The method and apparatus provide for modifying of the density values of successive pixels in accordance with an error diffusion operation. The modified density values are then subject to a thresholding operation wherein the thresholding operation employs position of a pixel to determine the digital value of the LSB of the rendered pixel. There is thereby provided a pattern structure to the LSB data. The rendered pixel values may then be compressed to provide for efficient storage in a memory or for efficient transmission over a communication pathway. The invention thus relates to improving the compressibility of the total image data by imparting structure to at least rendered image data where the error diffusion process would normally remove any structure to the LSB's of the image.