Rank-order error diffusion image processing

A method of preparing a renderable version of an image for rendering on a device having a reduced number of quantization levels as compared to an available version of the image, the method comprising:

• selecting a processing path for processing the available version of the image;
• selecting at least one diffusion mask based on a compatibility with the selected processing path;
• selecting a pixel of interest from the original image based on the selected processing path;
• selecting a set of neighboring pixels based on the selected pixel of interest and the selected diffusion mask;
• making a marking decision based on a pixel value of the pixel of interest;
• calculating an error value based on the marking decision;
• ranking the neighboring pixels according to pixel values of the neighboring pixels;
• and,
• diffusing error, based on the calculated error value, to at least one neighboring pixel based on the ranking of the neighboring pixels.

An image processing system operative to perform rank order error diffusion, the image processing system comprising:

• a pixel ranker operative to receive information about a set of selected neighboring pixels, and assign a rank to the selected neighboring pixels based on pixel values of the neighboring pixels;
• a thresholder operative to compare a pixel value of a pixel of interest to a threshold value to generate a comparison result;
• a marker operative to make a marking decision based on the comparison result;
• and,
• an error diffuser operative to calculate an error value base on the pixel value of the pixel of interest and the marking decision, and to modify a value of at least one of the selected neighboring pixels, based on the ranking of the selected neighboring pixel and the calculated error value.