Bottom: your ‘sigmoid’ image; top: your ‘log’ image with the tone curve on the right applied in darktable. Not a 100% match, but it could be refined. I hope this provides a visual explanation.
Bottom: your ‘sigmoid’ image; top: your ‘log’ image with the tone curve on the right applied in darktable. Not a 100% match, but it could be refined. I hope this provides a visual explanation.
