Grayscale to Red-Green-Blue (MATLAB Jet) color scale

Question

I was given a data set that is essentially an image, however each pixel in the image is represented as a value from -1 to 1 inclusive. I am writing an application that need

Answer 1

This probably isn't exactly the same, but it may be close enough for your needs:

if (-0.75 > value) {
    blue = 1.75 + value;
} else if (0.25 > value) {
    blue = 0.25 - value;
} else {
    blue = 0;
}

if ( -0.5 > value) {
    green = 0;
} else if (0.5 > value) {
    green = 1 - 2*abs(value);
} else {
    green = 0;
}

if ( -0.25 > value) {
    red = 0;
} else if (0.75 > value) {
    red = 0.25 + value;
} else {
    red = 1.75 - value;
}