How to un-dither JPEG image?

Factual Questions
1

I’m fiddling around with changing up the colors on a camo pattern for grins- I may end up repainting some of my son’s toys in the pattern eventually.

Anyway, it’s a very simple digital pattern of single-colored blocks- no blending, etc… but whoever saved it on the web did so as a JPEG and as a result, rather than being actual solid blocks, it’s made of blocks with edges of a slightly different color (dithering? JPEG artifacts?), so that I can’t just pick a new color in MS paint and use the paint bucket tool to just replace that color in each block.

Is there a relatively easy way to fix this?

2

Not in MS Paint. But programs like Photoshop can create a filter that reduces the number of colors of an image so that the edges sharpen. It kind of posterizes the image, but if it is a camo pattern, I would think that would be just what you want to do.

3

^^^ MS Paint can reduce the color space. When you Save As, select 16-color BMP.
It’s not on-the-fly but it works just fine.

4

I’d use Inkscape.

Import the bitmap, trace it to vector (you can tell it how many different colours to use), then use the ‘simplify’ function to smooth out any jaggies.

5

VectorMagic is another vector conversion service, and the best one I’ve ever seen. Give it a shot if Inkscape doesn’t work out.