Re: Adjusting contrast/brightness by gradient?

"surface9" <davsf@xxxxxxxx> wrote in message
news:d3a0b179-a7ba-4172-a7f3-0b6ba6aa022c@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
I have a photograph that has areas where the shadows are much to dark
- I can adjust the contrast and brightness so as to bring into clear
view those portions of the photograph, but that washes out all the
other areas of the photograph. What I need to be able to do is to use
a freehand tool to outline a closed area that will be the object of
contrast/brightness adjustments, but, not all the same. I need to
have the adjustments not applied at all to the edges of my closed
area, and for the brightness/contrast to be progressively appled to
pixels according to how far away from the edge of the closed area they
are, so that those pixels that are farther away than a predfined
"distance" (I need to be able to chose this value), will be subject to
the full application of the brigntess/contrast controls that I apply.
I need to be able to see the effect in real time, with sliders, so
that I can view and test the results - this way I can UNDO the bad
lighting that was done when the photo was snapped.

Is there a technique for doing this?

Yes, any number of well-developed techniques for adjusting shadows have been
developed over the years, before Photoshop existed and after, but let's step
back a bit and look at the bigger picture.

Brightness and contrast were included in version 1 of Photoshop, but they
are brutal tools to use on your image because they always throw away data.
Levels, which someone mentioned, is an improvement because you can adjust
the middle gray triangle, effectively trading shadow detail for highlight
detail (or vice versa) gracefully, compressing image detail in the
highlights (or shadows) instead of simply throwing it away.

Masking, and using multiple layers, can be very effective in some
situations, but as you have already noted, it takes considerable skill to
use a mask - particularly a mask that you draw yourself - without producing
an artificial edge.

Photoshop offers a number of other tools for you to use. Shadows and
highlights is a new, and extremely powerful, method of adjusting the overall
brightness and detail. I suggest you spend half an hour experimenting with
this tool. I'll bet thumb drives to punch cards that you'll get good
results right away.

And then, of course, there is curves. Curves are Photoshop's simplest, most
elegant, and most powerful color correction tool. Using a curve that is
steeper in the shadows, and less so in the rest of the image, will greatly
improve shadow detail, with no telltale artificial edges.

But first try the S&H command.
--
Mike Russell - www.curvemeister.com


.

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