creates a linear lookup table between color a and color b

makeLut_.ijm

run("Boats");
makeLut("#009100","#ccff42");

function makeLut(a,b) {
  a = Color.toArray(a);
  b = Color.toArray(b);
  reds=newArray(256);
  greens=newArray(256);
  blues=newArray(256);
  for (i=0;i<reds.length;i++) {
    reds[i] = a[0]+i*(b[0]-a[0])/256;
    greens[i] = a[1]+i*(b[1]-a[1])/256;
    blues[i] = a[2]+i*(b[2]-a[2])/256;
  }
  setLut(reds,greens,blues);
}