Not so many years ago, previous hardware used color paletter to display colors and it was relatively easy to swap colors and create animations like rainbows, well with technology evolution it came as a thing of the past and today it is quite cumbersome and complicated to replicate the same effect, even color replacements can be quite difficult to achieve as in old generation hardware. I spent a week thinking how to achieve the same and searched everywhere for a good implementation that will have the less impact as possible, well as a matter of fact I couldn't find any code but just a bunch of ideas. Even something as simple as creating blending effects became a nightmare in a matter of days, like linear burn A+B-1 blending, can be quite complicated to achieve in modern hardware and I am still unable to perform this in a way that memory, bandwidth and speed are not compromised, since the framework has to be very fast I came up with some solutions in my mind and will post some videos soon. Sometimes I think I just only need one command to do whatever I want, but that command doesn't exists in the pipeline, or is available in the next generation hardware.
So far color replacement is working, but I haven't tested it yet in XBOX in game, for only one color, adding more colors shouldn't be that difficult but there are quite many restrictions with the technology available in XNA and pixel shaders v2 with XBOX, like the number of parameters that can be passed through the shader, so using an image to remap color palette seems to be better solutions but doing it in RGB color space seems to be pretty bad if you are using different shades of the same color, so HSV comes to the rescue, but the number of operations performed to convert each pixel to HSV can be quite taxing to the GPU of the XBOX, so hopefully I can squeeze as much juice as possible from the GPU and implement a color palette, stay tunned.