Spot function endtone noise and growth

摘要

A method of preventing Moire patterns in a halftone image includes creating a digital screen including a collection of cells having pixels with threshold values according to a spot function, and dithering the threshold values corresponding with the endtones while not dithering the midtone gray values. Preferably, the amount of dither increases with the difference between the threshold value of the pixels from the midtones. The growth of the spot due to increasing gray values is controlled such that all cells grow at the same rate at the endtone gray values, and some cells grow at different rates at the midtone gray values.