MATLAB：如何将值缩放到颜色条并返回RGB 3列矩阵

Question

I have an array (A) of length 500 containing values between 0 and 0.25 I want to scale them to one of the inbuilt maltab colorbars (so that the max value falls at one end and the min at the other).

But then I want matlab to tell me what the rgb values it gives each value in A. ie a matrix of size 500x3

How can I do this, seems like it should be easy.

Answer 1

You can get the colormap rgb values for the colormap jet by typing: cm = jet(number_of_colors) . Now you just need to find the correct indice in the colormap-matrix for every value...

clear all
number_of_colors = 100;
cm = jet(number_of_colors);  % choose colorbar (jet)

values = rand(1,500)*50 + 20; % your data

values_min = min(values); % range of the colorbar
values_max = max(values);  

% Calculate the respective index in the colormap for every value
idx_in_colorbar = floor(1+ (values - values_min) / (values_max -values_min) * (number_of_colors-1));

matrix_with_rgb = cm(idx_in_colorbar,:)

Answer 2

Matlab actually scales the data a bit differently, so the right formula is:

idx_in_colorbar = floor(1+ (values - values_min) / (values_max -values_min) * (number_of_colors)); idx_in_colorbar(idx_in_colorbar > number_of_colors) = number_of_colors;

see more here: https://edoras.sdsu.edu/doc/matlab/techdoc/ref/caxis.html