Message
Re: [colorvision_group] Re: Gammas?
2006-05-27 by CDTobie@aol.com
In a message dated 5/27/06 2:56:24 AM, lowlife_inc@... writes:
And what Colorvision does not tell you is that other calibration
software companies have introduced "Native" and L* gamma settings that
they consider a better option...
L* gamma is approximately gamma 2.2, with the bottom eased off, so that the plane doesn't bump into the runway as it comes down, so to speak. Using it effectively seems to involve changing religions, and moving all your files to an L* space. Since no one I know uses L* spaces for their files, its not very practical for me to keep my files, or my monitors, at such settings.
Native gamma is a bit more complicated then native whitepoint. There are actually three gammas for an RGB monitor; one for each channel. You can get away with this for highend CRTs, where the curves are gamma shaped, and can be hardware tuned to the correct balance, so that gamma 2.2 and native gamma are identical. With an LCD the three are never the same, and none of the three are gamma shaped. The theory of native gamma (which would have died long ago if it weren't for its valiant champion Chris Murphy) is that you should leave the channels in your monitor uncorrected, lumpy, and misbalanced, and that you should then make similar corrections in the monitor profile instead.
There are a few issues with this system. First, it will leave all uncolormanaged elements (like images in Windows web browsers, for example, or even the Windows desktop, for that matter) uncorrected (and on an LCD this means REALLY uncorrected). Second, this scheme depends on the application to apply a more complex form of gamma corrections, one that some applications do not process. I can even recall a version of Adobe Acrobat that didn't process this type of profile gamma definitions correctly. Thirdly, this is not the standard method, proven and accepted by most experts.
So yes, these are possible methods, that others currently support, and that ColorVision will consider supporting when we can verify that they actually offer advantages, not just marketing spin. In the meantime, I wonder why LowLife bothers to belong to this list, when most of his posts are this type of ColorVision criticism?
C David Tobie
Product Technology Manager
ColorVision Inc.
CDTobie@colorvision.com