How can I change all pixels of one color to another color in a picture?

Question

I have an image which looks like this:

However the yellow line needs to be red and the cyan line needs to be green. I have MS Paint and IrfanView.

How can I change the colors of the yellow and cyan line without individually selecting all pixels manually?

I.e. what is a good way of changing all pixels of one color to another color?

Answer 1

ImageMagick can do all sorts of fancy color replacements.

Answer 2

In games, many years ago we used *.PAL file editors to change one color per another. This is mostly for if your images are color indexed. (IE: Gifs are always color indexed)

It was used (also did again while doing mobile games) to change cloth colors so to make different enemies using only the memory in disk of a single one.

There are many tools, but as an example:

http://www.agentur-simon.de/pedit/

Also, you say you use irfanview, there's a plugin:

http://www.ivanview.com/pal.html

Answer 3

Pick an image editing program like Photoshop or GIMP (latter one is free), and paint the line with "Color" mode.

Answer 4

paint.net will do it, you just need to do a fill, with 'global' mode instead of contigious mode