Low Noise Color Error Diffusion using the 8-Color Planes

Digital color halftoning is a process to convert a continuous-tone color image into an image with a limited number of colors. This process is required to generate an image reproducing the colors, the tone, and the details of the original continuous-tone color image. An elementary color halftoning method is to apply halftoning techniques independently to each of the color planes. For example, a full color image is separated into three continuous-tone images with C (Cyan), M (Magenta), and Y (Yellow) process colors, and each of them is independently converted to a binary image. Since this method ignores the relation among color planes, three process colors are overlapped randomly and it produces noisy and poor printing results. The main contribution of this paper is to present a new color error diffusion method. The key idea of our new method is to uniformly distribute pixels of 8 combination colors CMY, CM, CY, MY, C, M, Y, and W obtained by combining three process colors C, M, and Y. Also, the brightness of the resulting images are equalized using the error diffusion. The experimental results show that our new color halftoning technique generates better quality printing results compared to the independent color error diffusion method.