This kind of editing is exactly what RAW is for, so I hope the
photo you have is such... Did it come from a digital cam, or scanned?
I would suggest a wide gamut RGB with at least 16 bpp,
non-gamma-corrected (i.e. linear)... whether it be RAW or scanned.
On Thu, 13 Oct 2005, Frantisek wrote:
With some photographs in need of heavy brightness editing (e.g. heavy
burning/dodging and curves, e.g. underexposed photos), what is the
best colour model to edit in? Editing in plain RGB often makes huge
hue shifts, which make it ugly especially if the edit is local only.
Editing in L from LAB mode leaves all colours severely desaturated
upon "exposure" boost (but keeps the hue, unlike RGB), requiring a
Saturation boost afterwards (but it's hard to tell how much will be
needed, to bring it back to normal). I guess it's because of nonlinear
gamma that the RGB photos make hue changes upon changing brightness.
How about reversing the gamma curve to linear (when one knows the
exact curve), brightening and applying gamma again?
What I also tried is editing in HSB and HSL spaces. These preserve hue
and saturation upon editing of B/L (unlike LAB space), with the best
so far seemingly the HSB space, where the channels do not clip as with
RGB heavy levels/curves change, nor are there any colour shifts as
with RGB. I can recommend it, but I don't know if it's suitable for
all photographs - I know very little about these colour modes, what do others
thing
about editing in them? Could there be some problems? And if it is so
much better to change tonality in HSB, why the heck Adobe hasn't yet
implemented it directly?
Thanks for comments,suggestions,et cetera. Are there some Curves/...
plugins that make editing in other than RGB easier? Now it's a bit
tedious - the Adobe plugin "HSB/HSL" is quite awkward to use.
Frantisek
--
*************************************************************************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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