Image-processing system

PURPOSE: To quantize gray-level pixels by combining halftoning with spread error diffusion. CONSTITUTION: Multiple-bit image signals I(n, l) are received by means of an image buffer 100. A filter 102 corrects the image scale or tone reproducing curve of the image signals I(n, l) and line buffers 104, 106, and 108 store the signals I(n, l). Then signal adders 110, 112, and 114 generate signals I(n, l)+e(C) by adding error term signals e(C) from an error register 120 to the signals in a weighting way. The outputs I(n, l)+e(C) of the adders 110, 112, and 114 are connected to a corrected image signal accumulator 122 and, at the same time, to an halftoning processor 124. The processor 124 generates output printer signals B(n, l) from the corrected image signals I(n, l)+e(C) and forms the bit map of an image which is reproduced by means of a printer. COPYRIGHT: (C)1994,JPO