It would also be very nice if I could have some areas discretely colored, but others mixed. For example, I would like to keep the blue, red, green and orange regions for
minindex(m,j)==1,2,3,4, but the case currently colored black and assigned minindex(m,j)==5 would be better represented as a mixture of red and blue which continuously interpolates between them, as minindex(m,j) takes noninteger values between 1 and 2 (which are the integers which are colored with blue and red).
I've had another idea: superimposing plots with different colormaps. That would allow me to have one colormap with just a few discrete colors in one plot, and then a different colormap for the blue-to-red continuum. I'll try that and send an update if I get something to work.