Simply use
coloredLabels = label2rgb (I, 'hsv', 'k', 'shuffle'); % pseudo random color labels
Here is a full demo:
I =[...
0 0 0 0 4 4 3 3
0 0 0 4 4 3 3 2
0 0 4 4 3 2 2 2
0 4 4 3 3 2 2 3]
hFig = figure;
subplot(2, 1, 1);
imshow(I, [], 'InitialMagnification', 1600);
fontSize = 16;
title('I', 'FontSize', fontSize);
% colorize the matrix
coloredLabels = label2rgb (I, 'hsv', 'k', 'shuffle'); % pseudo random color labels
% coloredLabels is an RGB image. We could have applied a colormap instead.
subplot(2, 1, 2);
imshow(coloredLabels, 'InitialMagnification', 1600);
axis('on', 'image'); % Make sure image is not artificially stretched because of screen's aspect ratio.
title('Colorized I', 'FontSize', fontSize);
hp = impixelinfo; % Show color as use mouses around over image.
