White Point with Gradient - Feature explanation

[dda]

Hi everyone,
Can someone explain what the White Point with Gradient actually does and how it works?
My trial and error approach has given me some perspective but not the full story, I'm afraid.
An informed explanation would be welcome, I could not find anything in the manuals nor the forum (but may not have looked in the right places)
Thanks in advance
Cheers

[forum_adm]

Hi,

you click into the image for the first point and hold the mouse button.
Now move to the second point and release the mouse button.

The color for the white point correction is changed from point A to B by linear interpolation.

This method is useful, for example, for scanned papers with a very dark scan on the left-hand side and a lighter scan on the right-hand side.

Thorsten

[dda]

Thanks a million for this clarification.

Am I right to say that the correction only happens if x or y of point B is higher that x or y of point A?

In your example if the scanned paper is darker on both sides and lighter in the center.
- To render the left side whiter, White point with gradient works when dragging from left to right towards the center (from dark to light) the left side will become whiter. x(B) is higher x(A)
- To render the right side whiter you still need to drag from left to right (from center of paper to outer right border), from light to dark this time (as opposed to dark to light previously) x(B) is higher than x(A). This is what threw me off and lost me at first. I was expecting that it would work from Dark to light in all circumstances, so in this case dragging from right border towards center, x(B) is then lower that x(A) and it does not seem to work.

Cheers

[forum_adm]

The function is designed for i.e. left side dark and right side lighter. It supports currently only one linear gradient.