Thanks for the tip CM, I didn't know this technique but I found a good tutorial:
https://www.youtube.com/watch?reload=9&v=PigTqI8pmjU
In this case it doesn't change a lot, but I've done it

I am not an expert in Displacement Maps but maybe there isn't enough contrast in the boys face. If you have the time you may want to try a copy of the boy's face with levels, curves, or contrast applied and try the Displacement Map on that copy. Or you could duplicate they boy once again and set the top layer on a Hard Light Layer, Multiply, (or otherwise) to bring out more contrast. Then flatten those two layers and try again. I don't know if any of this will work, but you may want to try.

Thank you. I find the contrast in the boy's face sufficient. It is a portrait. Too much contrast can ruin a portrait, it hardens the face. It can be interesting in some cases, but here I whish my boy to remain sweet as an angel

Thanks

Thanks Wyndham