@afre

If you look at the paper, I give, you will see that the reference text, is the one you mentioned (McCann 1970)

In the “Ipol”, the “decomposition” is done with a Laplacian “threshold” to take into account the reflectance…and illumination. With the threshold you adjust the “quantity” of Luminance you don’t want to take into account.

It is the same theory…

But, but, but,… the algorithm of McCann is very complex, that of “Ipol” is simple (since we can consider that using a Laplacian, a Fourier transform and the Poisson equation is simple)

But the result, in the exemple “Ipol” I give, and my result are close to the results that you show

there are 4 parts in the Ipol algorithm:

- a) apply a “Laplacian threshold” (I have modified this algo to take into account the background, and the deltaE)
- b) Fourier transformation (also I modify)
- c) Poisson PDE
- d) Normalize luminance : after a) b) c) the luminance is completely changed. “Normalize” ensures that the final image will have the same “mean” and the same “variance”. Only is changed the variation of luminance (in shadows, in highlight)