color similarity in Lab space

Hi, I have been trying to do the following: import 200 images and calculate a matrix of color similarity/dissimilarity values between pairs of images by using CIElab. I guess what I need to do is to transform the RGB values into LAB and bin the new transformed pixels in a histogram for each image. Then I need a distance metric, like the Earth Mover's Distance. Do you think it is a valid measure? Plus, the distance has to be calculated over the three channel, right? Can anyone explain me each step to obtain a final matrix of distance? Thank you