Monday, June 20, 2005

L* - obsoleting gamma

The latest Basiccolor Display and ColorEyes Display give the user the option of calibrating to L* instead of a gamma value like 2.2 or 1.8. Gamma values are related to the functioning of CRT screens, and these are nowadays a quasi-obsolete technology.

The basic idea behind L* is to have a monitor space which does not employ the obsolete notion of gamma. In fact, L* seems to be derived from LAB, and is therefore a perception-linear space, at least as far as the luminance axis is concerned.

An L* working space and various test images can be downloaded here. I don't think that the use of an L* working space in Photoshop is really necessary to enjoy the benefits of a screen profile made with L* in photoshop.

I will try to make a translation of the german L* documents soon; then you can tell me what it all means. There is however one caveat — I have heard rumors, which I'm trying to confirm, that L* is patented — I wonder whether a _notation_ for a psychophysical quantity eg. color can be patented ? Would the decibel or music notation be patentable in the eyes of US law of 2005 ?

1 comment :

Anonymous said...


Earlier this year and after a long discussion at robgalbraith, we decided to merge L*-rgb and Bruce Lindblooms' Beta-rgb.

New L*-beta-rgb carries the L* tone curve while offering the extended primaries of Beta-RGB.

The guys from ColorSolutions generously realized this upon request and after checking with Bruce. So there should be no patent infringement at all.

If of interest, just let we know. I'd be pleased to provide a copy.