Multiple mode binary image processing

Print/no-print values are assigned to individual picture elements (pixels) representative of a document to be reproduced or displayed for text, continuous tone, and halftone data. The image data comprises gray scale values individually representative of pixels of a document to be printed or displayed on a bilevel device. The image data is partitioned into data blocks of 2nx2n matrices of contiguous image data. The average tone density of each data block is determined and a corresponding number specifies how many of the total number of pixels of each data block are to be printed. Each data block is subpartitioned into subblocks comprising contiguous quarters of the block subpartitioned. The pixels to be printed for each subpartitioned block are divided among the subblocks based on the ratio of the average densities of the subblocks to the average density of the subpartitioned block. In turn, each subblock is subpartitioned into newly formed quarter subblocks with the pixels to be printed for each subpartitioned subblock being divided among the newly formed subblocks based on the ratio of the average densities of the newly formed subblocks to the average density of the subpartitioned subblock. These operations are repeatedly performed on all subblocks until each pixel to be printed has been assigned to a specific pixel location of the image data representative of the document.