Hi First of all thanks for the overwelming response. And I would also like to say thanks for this great library.
I have implemented the multiple transform in a test mockup and it works. On Friday 10 June 2005 18:59, Jan-Peter Homann wrote: > Both the ways of converting to CIELab or using HSL are possible. > May be, you can the user a choice, what to use. Well according to Poynton HSL should be avoided. > 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 Interesting because I also understand contrast adjusting as spreading the lightness away from 50% towards 0% and 100% and brightness adjustment as moving the total lightness level This is at odds with the mail refered to by Marti where: newL = L*contrast + brightness I would have thought: newL = (L-50%)*contrast + 50% + brightness to be more correct. I can easily do the math to reformulate, but I just want to be sure. Oh and this doesn't really make a soft S curve as requested. For that I need to make a LAB transform, do the S, and back from LAB, rather than one single transform. Would it be possble to do the S with an abstract profile? -- best regards / venlig hilsen Casper Boemann ------------------------------------------------------- This SF.Net email is sponsored by: NEC IT Guy Games. How far can you shotput a projector? How fast can you ride your desk chair down the office luge track? If you want to score the big prize, get to know the little guy. Play to win an NEC 61" plasma display: http://www.necitguy.com/?r=20 _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
