Algorithm to measure images colourfulness, adapted from "Measuring colourfulness in natural images" (Hasler and Susstrunk, 2003) http://infoscience.epfl.ch/record/33994/files/HaslerS03.pdf

getColourfulness.m

function C = getColourfulness( im )
%
% C = getColourfulness( im )
%   
% MATLAB algorithm implementation of the 
% "Measuring colourfulness in natural images" 
% (Hasler and Susstrunk, 2003) 
%
%   Input:
%       im  - image in RGB
%
%   Output:
%       C   - colourfulness
%

    
    im = double(im);
    R = im(:,:,1);
    G = im(:,:,2);
    B = im(:,:,3);
    
    % rg = R - G
    rg = abs(R - G);
    rg = rg(:);
    
    % yb = 1/2(R + G) - B
    yb = abs( (0.5*(R + G)) - B );
    yb = yb(:);
    
    % standard deviation and the mean value of the pixel
    % cloud along direction, respectively
    stdRG = std(rg);
    meanRG = mean(rg);
    
    stdYB = std(yb);
    meanYB = mean(yb);
    
    stdRGYB = sqrt((stdRG)^2 + (stdYB)^2);
    meanRGYB = sqrt((meanRG)^2 + (meanYB)^2);
    
    C = stdRGYB + (0.3*meanRGYB); 
end