> To reduce banding, the idea is that for each pixel, you choose between the rounded up or rounded down value semi-randomly, with a probability depending on how

> To reduce banding, the idea is that for each pixel, you choose between the rounded up or rounded down value semi-randomly, with a probability depending on how close you are to each value. This oversimplifies it a bit. Most dithering algorithms are deterministic. They are based on choosing a value for a pixel, remembering the difference between the ideal and the chosen value and then spreading out that difference to surrounding pixels. Random dithering is more commonly used in audio signals, AFAIK, not much in image processing.