Hi Casper,
If so, how do I do it with lcms. I was thinking of making a transform that
converts to an abstrat colorspace based on CIELAB, but with an extra scale on
L* and then back again. Can this be done and how?
Not only can be done... it is already done :-)
There is a function called:
cmsCreateBCHSWabstractProfile()
This function accepts following parameters:
int nLUTPoints : Resulting CLUT resolution
double Bright : Bright increment. May be negative
double Contrast : Contrast increment. May be negative.
double Hue : Hue displacement in degree.
double Saturation : Saturation increment. May be negative
int TempSrc : Source white point temperature
int TempDest : Destination white point temperature.
And returns a ready to use cmsHPROFILE handle to an abstract profile doing the
translation.
Then you can use cmsCreateMultiprofileTransform() to bind the RGB -> Lab, the abstract
profile and the Lab -> RGB. That works for other spaces like CMYK too.
See this post about the subject:
http://sourceforge.net/mailarchive/message.php?msg_id=11737885
Right now, it works but is not perfect. Incoming versions probably would use other more
perceptually-uniform spaces, like CIECAM02.
BTW. I wish to congratulate you and all Krita folks for the great work you are
doing,
there is a *huge* need of color-savvy application over there. Anybody is going to
attend the libresoftware meeting July, 5th to July, 9th in Dijon, in the East of France?
I will be there, so it will be a great chance to get in touch!
Best regards,
--
Marti Maria
The littlecms project.
www.littlecms.com
----- Original Message -----
From: "Casper Boemann" <[EMAIL PROTECTED]>
To: <lcms-user@lists.sourceforge.net>
Sent: Friday, June 10, 2005 4:03 PM
Subject: [Lcms-user] changing brightness
Hi
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?
If so, how do I do it with lcms. I was thinking of making a transform that
converts to an abstrat colorspace based on CIELAB, but with an extra scale on
L* and then back again. Can this be done and how?
--
best regards / venlig hilsen
Casper Boemann
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