Hello Caspar, hello List
As I´m not a developer, I use the terms of a user, to describe, what
should be done.
Both the ways of converting to CIELab or using HSL are possible.
May be, you can the user a choice, what to use.
Important for good results in both ways is the use of curves for
correction of brightnessand contrast.
This is necessary to avoid clipping.
For adjusting brightness, the midtones should be brighter blackpoint or
whitepoint should stay stable
For more contrast you should make a curve like S.
- Midtone is stable,
- blackpoint and whitepoint are stable
- bright colors brighter
- dark colors darker
Sometimes the histogram shows, that blackpoint and/or whitepoint have
still some space. In this case, a function for autmaticly setting
whitepoint and blackpoint would be helpful for the user.
Can be named "tonal adjsutment.
So it makes sense, to make one menue with a knob "tonal adjsustment" and
sliders for brightness and contrast.
:-) Jan-Peter
Bob Friesenhahn schrieb:
On Fri, 10 Jun 2005, Casper Boemann wrote:
I'm a developer of krita - the KOffice paint application - which uses lcms
I'm about to rework our brightness/contrast dialog, but looking at how
other
programs does it I'm a bit confused as to what is correct behaviour
Now what I intend to do is: convert from whatever colorspace we are
working in
into CIELAB, change L*, and convert back into the original colorspace.
does this sound like the correct thing to do?
GraphicsMagick/ImageMagick perform this adjustment using HSL. So the
'L' value gets adjusted.
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