Chuck Norcutt wrote:
> Whatever you might have said about color match (actually, look for "match
> color"
Oops, sorry about the word reversal.
> or you won't find it in PS help) has been lost to my leaky memory since I
> a) didn't remember such a thing existed and
> b) haven't been able to figure out how to use it.
>
> Using curves is actually pretty simple and can be done in about 30 seconds.
> <snip details>
>
That technique works fine where there there is no luminance detail at
all and on very small areas. In this set of images of David's, that's
mostly true. On 3, though, painting a single color onto the woman's
chest would look very artificial, whereas Match Color retains the subtle
luminance shading, even into the shadows, while recreating the lost skin
tones.
The details of highlight recovery vary with different RAW converters.
According to dpreview's comparison, ACR was the most aggressive in
recovering color detail, even where correct color is lost through
unrecoverable clipping of 1-2 channels. Some other converters are more
conservative, simply going completely to shades of gray in the areas
where at least one channel has clipped. Dcraw has options for highlight
color recovery from very conservative up to a very aggressive level of
color inference, which varies in results from very good to useless.
Where color is lost, but luminance detail remains, Match Color can do
apparent magic. Ian's snail is a good example. Simply using the PS
Highlight tool recovers lots of compressed luminance detail, but with
almost no color. Whether this is a result of highlight recovery in RAW
conversion or of JPEG processing doesn't matter here, only that it
provides such a clear example.
In the original, both color and luminance detail are lost to the eye
over a large part of the shell. Roll over the image to see what is
recoverable with Highlight. Almost the whole of the shell now has
luminance detail showing the texture and patterns of the subject, but
the bright area is almost pure grayscale. Click on the image to see what
Match Color can do.
<http://www.moosemystic.net/Gallery/Others/Swiss/Snail.htm>
Match Color takes the color palette of a source image or selection and
overlays it on the luminance information of a target image or selection.
It also has a Luminance slider to move the resulting palette brighter or
darker and other adjustments. If done on a separate level, the same
selection used for Match Color target can be set as a mask. I usually
choose a slightly larger than necessary target area, to allow edge
refinement of the mask. For the snail, I chose as source most of the
non-clipped shell and for target, the blown area. The colors are a
perfect match because they come from the same subject in areas not
overexposed.
I can't imagine correcting the snail by hand; the labor would be much
greater than simply copying color palette across. I don't think that
simply manipulating Levels & Curves by channel could do it right, as the
mix appears to change with brightness.
I also know that there are variations in subtlety of color perception.
David, AG, C.H. and others here appear to have more of that than I do.
When I used to go birding with a friend, it was amusing when a bird flew
by for just a glimpse. She would pick up the colors better than I and I
would pick up the shapes, bars and marking details that she missed.
Using Match Color, I don't have to rely on my color vision to get the
replacement color right, it comes from the image itself.
Moose
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