Calculating color difference of skin using L*a*b* from RGB

[annie86chang]

Hello,

I am new to ImageJ (just downloaded today) and am trying to figure things out.

My Research Project: Patients with vascular skin lesions, treat with laser, take before and after photographs. Calculate the color difference between the treated areas compared to unaffected skin.

I found a paper that I would like to duplicate their methods of evaluation:

http://ybil.yonsei.ac.kr/Publication/Papers/Out/Objective%20Evaluation%20of%20Treatment%20Effects%20in%20Portwine%20Stains%20Using%20a%20Personal%20Computer%20Color%20system.pdf

So far I have been able to quantify mean RGB within a chosen ellipitical area using the histogram, but I need the L*a*b* values to determine the color difference (delta E). I downloaded multiple plug-ins (Color transformer, color inspector 3d, color space converter) but have had little luck. Please help! Thanks so much :)
-Annie