I have a color bar varying from yellow to red to black to white and is incresingly quantized in the same order. How can I import the same scale and all the shades in MATLAB so that i can upload an image and get the max and min values in that image?

I have a prefixed quantized color scale with colors varying from yellow to red to black to white. I want to upload this scale into MATLAB and use this scale to do my processing of the images.