How do I assign specific RGB colors to specific numbers in a matrix - and display?

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Daniel
Daniel on 14 Apr 2014
Answered: Image Analyst on 14 Apr 2014
I am trying to create a color file from a text/matrix file consisting of numbers. How do I assign specific RGB colors to specific numbers?

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Answers (1)

Image Analyst
Image Analyst on 14 Apr 2014
Let's assume your text file is a 2D array of integer numbers in the range 0-255. Use something like improtdata() or csvread() to get it into a uint8 array. Then to associate each number, make a lookup table. If you want a "standard" one, you can do
myColorMap = jet(256); % or autumn or hot or winter or whatever one you want.
Then you can either display it with a pseudocolor look up table:
imshow(yourImage);
colormap(myColorMap);
colorbar;
or you can create your own colormap if you want something specific. It's a 256 row by 3 column array with each number in it being between 0 and 1 for R, G, and B. E.g. to make gray level 0 blue:
myColorMap(1,:) = [0, 0, 1]; % Make gray level 0 be blue.
Or you can convert the indexed image into a true full color RGB image:
rgbImage = ind2rgb(yourImage, myColorMap);

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