"Error Diffusion Dithering" is a common means of improving the appearance of an image that has been constrained to use only a few colors or pixel values. Use this tool to dither your own image.

Upload an image of your own...
Or point the tool to a valid web address:
Select a dithering algorithm:
Convert to grayscale:
Rescale image resolution relative to the window:
Set the # color bands:
Set background grayscale: