When I use "Wavelet Decompose" to make a frequency separation on Gimp, I use, let's say 3 levels, which generate 3 layers of detail. But IMHO they are too many (On Ps I am used to having only 1 layer for details)
So I have tried different methods to merge these layers into only 1.
The first method is leaving on only the "details" layers and right-click selecting "New from Visible".
The other method is "Merge Visible Layers" (1).
Both methods render acceptable results, but they are not precise. If I generate a "Difference" layer (2) comparing the resulting image vs the original, some slight differences appear (3 and 4).
Which would be a more precise method to merge the layers?