HELP to resolve this code

m=original  color image
en=enhanced  color image
have written code for measure absolute  mean brightness error(AMBE)

function E=eme(x,m)
   em=mean2(x);
   mm=mean2(m);
   E=abs(em-mm);
end

Here E is absolute difference between mean brightness of two color images I think this code will take mean brightness of one channel of color image butcolor image has three channel so how will take the mean brightness value of all three channel

[Poonam]

PLEASE HELP ME OUT TO RESOLVE THIS CODE

Answer 1

[Thorsten]

function d = brightnessdiff(I1, I2)
 d = rgb2gray(I1) - rgb2gray(I2);

[Poonam]

why should I convert it into rgb2gray i want mean brightness difference of color image

[Image Analyst]

Brightness is not very precisely defined. Using rgb2gray() will give you the "brightness". You could also use rgb2lab() and use the L channel, or rgb2hsv() and use the V channel. It depends on what you want. Or perhaps you want to convert to LAB color space and look at the Delta E (color difference) which takes into account the total color difference, not just the brightness component. For example Delta E (like in my File Exchange) takes hue and chroma (saturation) into account, as well as brightness, in determining a total color difference.