Working version

Command line usage

tcolorswap red-value green-value blue-value input-file output-file

• red-value - red color component value
• green-value - green color component value
• blue-value - blue color component value
• input-file - input gif file to modify its color map
• output-file - output gif file to output the result

For Windows users, place both .dll file and .exe file together, then execute the program from there.
For Linux users, you can build the program yourself (just need giflib or install it via apt install giflib giflib-dev. For this release, it uses v.5.1.4), or download from the included binary + .so file.

Example

tcolorswap 0 253 255 input.gif output.gif

This will move color whose value is RGB(0,253,255) in colormap of input.gif to be at the first location, then write to output.gif.

Note
You can validate that the output is correct