Thanks, John. While these may be the result of naturally uneven skin tones, in the photo it seems to give a sense of patchiness to the skin. I do not know much about how we perceive, but I suspect that when we look at a real person our brain tends to even out these differences to some extent. I would like to change the rate of transition from the dark to the light area and vice-versa in the photos, so they look more natural to me. Something along the lines of this:
As you can see while the highlights and local colors are there, just the patchiness is reduced. I did this following an online tutorial I found that involved separating the skin, blurring it, and adding the skin texture back on.