ajit, if there is a brightness change, there is a color change. If you want to detect a hue, regardless of it's brightness, then you can use my HSV color segmentation demo and just threshold on the hue value. However skin is a boomerang-shaped gamut and can't be gotten by any simple carving up of the gamut in any 3D color space, no matter which one you pick. You'd need to carve out the boomerang shape, not just a hue sector or a delta-E ball shape.
works very accurate if said to choose any color however if there is brightness change for same color in rest of the picture than selected, then it does not detect(skin color with different brightness),can u please help?