how to calculate "Luminance Distortion" for original and contrast enhanced image?

we proposed a method for contrast enhancement of medical images. now we need matlab code for evaluation metrics namely "luminance distortion" and "Contrast from Fuzzy Gray Level Co-occurrence Matrix". pls suggest me matlab code for these measures.

if any other measures matlab code available suggest me. Reference:"Brightness Preserving Dynamic Fuzzy Histogram Equalization" by Debdoot Sheet. looking forward your reply. thanks in advance.