> From: "Seymour Fine" < syfine%40gmail.com">syfine
gmail.com>
>; Date: Thu, 11 Oct 2007 20:57:37 -0400
> Can someone please list the steps in Gimp for
> lightening an over-exposed photo (i.e., one that's
> too dark).
Well, the first warning you need to hear is that
with only eight bits per channel, GIMP images are
pretty limited in how much you can vary their
"value" without turning some dark patch to a really
ugly greyish purple expanse. So, if your photo is
badly too dark, you'll be unlikely to be happy
with any result.
As answered elsewhere, the Image window's
Colors => Brightness-Contrast
menu item, or in older versions of GIMP, the
Layers => Colors => Brightness-Contrast
menu item, will let you do the change globally
for the photo with the same amount of change
everywhere.
For somewhat finer control, you can pick the Colors
=> Curves menu, and pull up parts of the "Value"
curve to lighten only those parts of the image that
correspond to that part of the curve's amount of
darkness. Clicking on the (initially straight) value
diagonal like will add points that behave like
handles, and can be dragged up or down (or sideways,
with usually unhappy outcomes). Each point added
anchors its part of the curve unless it is the
handle being manipulated, so some points can be
added merely as anchors with no intention to
manipulate them. I usually start by anchoring the
diagonal line midpoint, then putting a handle at
the 1/4th way point and lifting that part of the
curve, to lighten the dark parts while leaving the
light parts unchanged.
It is even possible to use GIMP's selection tools
to select parts of the image, then use either of
the tools mentioned above to manipulate only the
selected parts. It helps a _lot_ when doing this
to "feather" the selection, so that you don't end up
with an ugly boundary being created right along the
selection edge. Feathering the selection's edge
makes whatever change you apply to the selected area
damp out gradually across te feathering part, which
turns out to be really helpful.
xanthian.
