Many digital cameras have similar issues, especially consumer level
ones. With these kinds of cameras it is worth paying attention to the
old adage: "expose for the highlights". I find that if I treat my
digital camera as if I were shooting slide film the exposure rules are
about the same.
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Here is the original image.
I saw my cat go up into a lemon tree. Thinking there might be
an interesting shot there, I grabbed the camera and shot him
from several angles, including this shot through a hole in the
foliage. When I saw the image later on the monitor I realized
what a nice natural three-dimensional frame I had.
The camera was set on automatic exposure. While it did a great
job of exposing for the dark cat in the shade of the tree, there
are several spots where specular reflections of the bright
sunshine overhead blew out. The worst and most noticable is the
one off of the leaf at the top of the image. There are some
less objectionable, but bothersome burned out areas to the lower
right of the cat's face.
Great image...could I rescue it?
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Using the color picker tool, you can see that there is no usable
information left in the highlight. Pure white, of course, is
255/255/255.
If there had been some detail left here I might have tried a
variation on the contrast masking
technique or the "digital"
neutral density filter first.
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The first step is to create a channel mask to be able to mask
out parts of the image we don't want to affect. I'll use this
for the main "pixel graft".
Duplicate the original image (Image/Duplicate or Ctrl+D).
In the duplicate, select Image/Colors/Threshold. In the
threshold dialog box, drag to select the very right (extreme
highlights) portion of the histogram. Alternatively, you can
type in the lower bound, as I did here (250).
This causes all the pixels in the image from 250-255 to go white
and all the others to go black.
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Go back to the original image, and bring up the Layers and
Channels dialog (Layers/Layers, Channels & Paths, or
Ctrl+L).
Click on the Channels tab and add a new channel by clicking on the
new channel button.
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Go back to the threshold image, Select/All (Ctrl+A) and
Edit/Copy (Ctrl+C).
Edit/Paste it into the original image (it should go into the new
channel).
Click on the Layers tab and anchor the floating selection.
You can close the threshold image now.
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Click on the Channels tab again, and right click on the new
channel and select Channel to Selection (Ctrl+S). You may want
to also click on the eye beside the channel to turn off
visibility of the channel.
Now feather the selection (Select/Feather). I used a value of
15 pixels or so in this case.
Finally (important!), click back on the Layers tab and select
the Background layer, so the selection and further operations
will apply to the image and not the channel mask.
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Now the real work begins.
We've lost these pixels entirely, so we're going to have to
graft some on from somewhere nearby using the clone tool.
 A description
of how to use this tool is beyond the scope of this document
(see the documentation links at the
bottom the parent page).
I cloned from the light part of the leaf just beyond the dark
band to the right of the blown out area. This gave me a similar
light-dark-light transition. You can see the clone tool options
and the brush (Dialogs/Brushes) I selected (at right).
Zoom in and clone until you have the area filled with a
realistic facimile of the missing detail. Most likely it will
have a noticable transition around the edges. That's OK, we'll
fix that up next.
Select/None and zoom out to inspect your work.
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This step is where the most difficult work occurs. I must by
necessity abbreviate this step, since it involves iterations of
applying the following tools:
-
 smudge
- clone
-
airbrush (w/color picker)
-
 convolve (blur)
Basically, smudge is your friend after a serious cloning job
like this to clean up the transitions. Smudge around all the
edges of the clone. The clone tool can also be used again here
and there for "mop-up" work.
I use the airbrush and convolve/blur tools to do fine touch up
on the smudge job and make it totally seamless with the rest of
the leaf.
Tips:
Bottom right: zoomed view after the clone (previous step) and
after this step.
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I went on to address the specular highlights to the lower right
of the cat's face: spots of sunlit grass that burned out. These
are not as bad, but I noticed them on a 16x20 print I had made
and they bothered me, so toned them down a little.
Here are the original and finished images.
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