I like the color schemes that are used as palettes in gnuplot’s pm3d plots. I wanted similar color schemes that can be used as colormaps in matlab.

After reading this article, I found thatÂ one can easily incorporate the traditional rgbpallette schemes in matlab

To start, there are several schemes in gnuplotÂ that can be used in pm3d plots and they are:

7,5,15 ... traditional pm3d (black-blue-red-yellow) 3,11,6 ... green-red-violet 23,28,3 ... ocean (green-blue-white); try also all other permutations 21,22,23 ... hot (black-red-yellow-white) 30,31,32 ... color printable on gray (black-blue-violet-yellow-white) 33,13,10 ... rainbow (blue-green-yellow-red) 34,35,36 ... AFM hot (black-red-yellow-white)

The numbers represent different mapping functions for red, green and blue and the functions are

0: 0 1: 0.5 2: 1 3: x 4: x^2 5: x^3 6: x^4 7: sqrt(x) 8: sqrt(sqrt(x)) 9: sin(90x) 10: cos(90x) 11: |x-0.5| 12: (2x-1)^2 13: sin(180x) 14: |cos(180x)| 15: sin(360x) 16: cos(360x) 17: |sin(360x)| 18: |cos(360x)| 19: |sin(720x)| 20: |cos(720x)| 21: 3x 22: 3x-1 23: 3x-2 24: |3x-1| 25: |3x-2| 26: (3x-1)/2 27: (3x-2)/2 28: |(3x-1)/2| 29: |(3x-2)/2| 30: x/0.32-0.78125 31: 2*x-0.84 32: 4x;1;-2x+1.84;x/0.08-11.5 33: |2*x - 0.5| 34: 2*x 35: 2*x - 0.5 36: 2*x - 1 * negative numbers mean inverted=negative colour component * thus the ranges in `set pm3d rgbformulae' are -36..36

For example, if we choose, 7,5,15 , ie, traditional pm3d (black-blue-red-yellow), the three numbers correspond to functions used for red, green and blue respectively. So in this case, red(x)=sqrt(x), green(x)=x^3 and blue(x)=sin(2*pi*x), where x has range from 0 to 1. Note that red(x)/green(x)/blue(x) should not be negative numbers, so if they are negative make then zeros.

With that knowledge, here is a matlab code that creates 7,5,15 and 3,11,6 colormaps and uses it in the display of an image.

This results are shown below. Other color schemes can be similarly incorporated into matlab codes.

Great!, i was looking for something like this, i needed the color schemes, i’m using pyxplot and it was so difficult to find a site that explains the functions used by color schemes.

Manyt thanks

Very very useful, thanks alot!