createcolormap.m

This function allows to create colormap Nx3 array (RGB) with an arbitrary combination of colors. RGB values between the specified colors will be smoothly connected by linear interpolation.

Example

cmap = createcolormap(C);
cmap = createcolormap(n,C);
cmap = createcolormap(colorA, colorB);
cmap = createcolormap(n, colorA, colorB);
cmap = createcolormap(colorA, colorB, colorC, colorD, ...);
cmap = createcolormap(n, colorA, colorB, colorC, colorD, ...);

where n is the number of segments for the output color scheme, and C is the RGB matrix of color junctions.

Usage

• blue-white-red (polar)

  b = [0,0,1];
  w = [1,1,1];
  r = [1,0,0];
  
  bwr = createcolormap(b,w,r); % 256x3 array
  
  colormap(bwr)
  colorbar

  If you want to use dark blue and red colors, try below:

  b = [0.0,0.0,0.5];
  w = [1.0,1.0,1.0];
  r = [0.5,0.0,0.0];
  
  bwr = createcolormap(b,w,r); % 256x3 array
  
  colormap(bwr)
  colorbar

  To create a more discrete color structure, input the number of elements in the first argument as shown below.

  bwr = createcolormap(16,b,w,r); % 16x3 array 

• more complicated combination

  colorA = [0.0,1.0,0.0];
  colorB = [1.0,0.5,0.5];
  colorC = [0.5,0.5,0.5];
  colorD = [1.0,1.0,0.0];
  
  cmap = createcolormap(64,colorA,colorB,colorC,colorD); % 64x3 array
  
  surf(peaks); 
  colormap(cmap);
  colorbar;

• RGB matrix

  cmap = createcolormap(rand(10,3)); % 10 random colors
  
  surf(peaks);
  colormap(cmap);
  colorbar;

License

MIT

Author

Takuya Miyashita
Disaster Prevention Research Institute, Kyoto University

Update

v0.1 2021/10/01
v0.2 2021/10/09