I think this is wrong. Let me show an example using the raw from
With exposure raised a bit + filmic white relative exposure set automatically:
Tone equalizer without preserve details:
With eigf enabled:
In the version without detail preservation, a darker pixel, between -5 – -4 EV, was brightened by a lot; the less dark ‘relative highlights’ on the rocks, at about -3 EV, were brightened less:
dark part:
lighter part, the ‘bright’ spot on the rock – it’s at -2 EV, and does not get brightened at all:
Therefore, the difference between the two was reduced → less contrast.
WIth _eigf: on, the darker area’s mask (‘average of its surroundings’) is also about -5 EV:
But the surroundings of the ‘bright spot’ are averaged, thanks to the mask, to -3.4 EV, and it still gets a boost of ~1EV:
If I turn off eigf, modify the curve to lift the bright spot’s -2 EV exposure value by ~1EV (so it’s brightened my the same amount that we had with preserve details), contrast is regained:
With that modification in place, the image still retains way more detail with eigf:
Without detail preservation, but with +1EV lift at -2EV:
