Loss details from texture from painting, texture from masking


As title, it’s since quite time that I have this particular issue. When I try to create and export a textur map from my cavity map, made with masking, instead of this:

I have this:

Now, the funny thing is that if I put in morph UW mode I don’t have any loss of details:

and i could try to export the image with “document -> export” but try to obtain the exact scale of the uv map it’s kinda of nightmare…

Somebody nows how extract this texture without loss of details and whit the right proportions?

Thank you very much and sorry for my broken english