how to remove shadows from face image in matlab ?

I want to detect lip in the face , in step one I convert the RGB image to Binary image but there is a problem , the quality and light effect on output mostly. some times when a person laugh the shadow changes the light so the result changes.I want try to change my code to create binary image according to light and shadow in the image to gain correct out put

after execute my code :

as you can see around of lip we have shadow , how do I remove shadow of face ? or how do I set variable on my code ?

I attached my code .

Answer 1

[Image Analyst]

There's nothing in MATLAB built in to do that. I'd recommend you find the algorithm for "Shadows and Highlights" that Photoshop uses. It's probably discussed online somewhere - I don't have it handy. Then code that up. It does a pretty good job.