Patent ID: 7557962
Filing Date: 2009-07-07
Classification: G06K,H04N

Abstract:
1. A system for halftone screening comprising: means adapted to receive image data having a desired number of tonal levels representative of a continuous tone image; compression means adapted to compress received image data so as to be defined in M×N tonal levels, wherein M and N are integer values corresponding to a length and width of a halftone cell, and wherein the desired number of tonal levels is greater than M×N; linearization means adapted for adjusting the M×N tonal levels so as to be visually linear and formed by two dimensional rectangular foreground dot regions surround by at least one adjacent background level within a plurality of halftone cells at a plurality of lightest tonal levels and formed by linear foreground regions extending linearly between oppositely disposed halftone cells at remaining tonal levels; a memory including a look-up table, the look-up table including an array containing halftone data corresponding to tonal levels and uniquely associated screen frequencies and line shapes, wherein device dots are added and moved within each halftone cell in the look-up table, in each of a highlight region, a midtone region, and a shadow region, such that a number of dot centers is altered progressively between the highlight region, the midtone region, and the shadow region, and a position of dots within each region is altered progressively for tonal levels within each region; and means adapted for communicating the compressed and linearized image data containing each tonal level to the look-up table having distinct halftone frequencies corresponding to each of the highlight region, midtone region, and shadow region, such that each region outputs corresponding halftone data in accordance with its corresponding halftone frequency.