One area, not the frame
The lift is placed. It brightens a soft circle around the tap and leaves everything outside it alone. That is useful for exactly one situation: the frame is fine and one part of it fell into shade.
If the whole image is heavy, stop. Four placed lifts will not do what one whole-frame correction does, and the four will leave four soft circles you can see once you know they are there. One spot, or the whole picture settles which case you have in about thirty seconds.
What a placed lift is good at
- A corner shaded by the photographer's own body or by a doorway.
- A face-down document photographed on a desk, where one side of the sheet is darker than the other.
- A subject standing under an awning while the rest of the frame is in daylight.
- A single dark patch left after a whole-frame correction has already been done somewhere else.
Questions about the lift
- How much does one lift raise?
- A fixed amount, strongest at the centre and nothing at all at the rim, on a curve that moves the dark end and leaves the bright end where it was. There is no number to set because a number to set is a slider, and a slider here would be the beginning of a different product.
- How wide is the patch?
- Four times the disc the other fixes use, which is worked out from the long edge of your file. On a twelve-megapixel photograph that is a soft circle roughly one-tenth of the frame across.
- Two lifts side by side?
- Allowed, as long as the second tap lands outside the first patch. Overlapping the same ground is refused, the same as anywhere else on this page.
- The shadow has a hard edge and the lift has a soft one.
- Then this is the wrong instrument. A cosine falloff cannot follow a straight line cast by a roof. A tool that finds the edge first would be a different kind of program.