Dithering can have creative effects. Although dithering is intended to be a way of reducing the number of colors in an image while minimizing the loss of quality, or minimizing the change to the appearance of the image (by using a pattern of dots mixed together to simulate extra colors), it can also provide a creative effect when used in extreme and heavy-handed ways for which it was never intended.
I’ve often used the dithering effect (called the reduce colors option) in Irfanview to make images that appear to be made of sand. Normally this sort of extreme dithering effect is unwanted (dithering aims to be unnoticeable) but like many things in computer art, new styles can come from very unexpected features and it’s what the effect does rather than what it was intended for, that’s important.
(First Image) This is the raw image from Sterlingware before any processing has taken place.
(Second Image) Here I’ve India Inked the image using the Bubbles pattern and Queen color setting. If I apply a normal amount of dithering as shown here, I keep the subtle gradients with only a minor appearance of a pattern and can reduce the file size to make it more bandwidth and storage space friendly. This color reduction is from True Color (24-bit, I think) to 256 (8-bit?) with the dotty Floyd-Steinberg pattern.
(Third Image) Oh no. This is too much. I’ve gone too far. Instead of that huge wack-load palette of 256 colors, I’ve strangled it down to only 16 and done away entirely with any dithering pattern and chosen to use only solid color areas (no mixing or “no dithering”). The result (this time) is a nice silkscreened or blotchy watercolored effect.
You know; I guess that wasn’t really dithering at all, strictly speaking. But I still consider it part of the same process of color reduction effects even if it’s really a complete lack of dithering and is actually the opposite effect of separating colors not mixing them. Incidently, the no dithering option produces a file size that is usually significantly smaller when saved as a png or gif, as these formats specialize in compressing image areas composed of solid lumps rather than gradients. But if you’ve got a high-speed broadband cable or DSL internet connection, you don’t really need to care about file size, I suppose. I guess it’s just a habit I picked up in my dialup days.