Multipass color printmasks based on location rules to minimize hue

Abstract

Scanning printheads form a color image as inkdrops in a pixel grid on a print medium. Pixel row spacing equals nozzle pitch. Apparatus holds and provides (or creates in real time) a printmask using location rules that prevent addressing, within each scan, immediately neighboring pixels in any horizontal, vertical or diagonal direction. The mask is applied to control the heads. In other aspects of the invention, the rules also prevent addressing, in each scan, horizontally neighboring pixels within the entire width of the mask; or vertically neighboring pixels within its entire height; or immediate neighbors in any direction across a boundary--horizontal, vertical, or either--between abutting masks. Specific masks are set forth implementing these aspects. Another form of the invention yields a two-pass mask with this pass-number pattern: ##EQU1## Another form is a mask-creating-and-using method: generate a number series to define rows/columns of a pixel grid for printing in successive head passes, test the numbers against rules to minimize ink coalescence, and accumulate the numbers as an array to define a pixel grid--all automatically. Also check performance of arrays so generated, select a preferred one, and store it in a tangible medium for later automatic recall to control a printer.