Richard Hughes wrote: > Yes, an interesting read, thanks. It doesn't seem to address the fact > that LCD displays can't show absolute black -- so the nice graphs > showing a power curve that goes through (0,0) is wildly different to > reality.
Yes. The only reference to this I'm aware of in industry literature is BT.1886, but I haven't really gone searching. There are several papers around on characterising CRT responses which may have dealt with it to some degree, although it can be swept under the carpet with CRT's due to the ability to get low black levels. > dim surround. If it is displayed without correction in a bright > ambient, it will appear contrasty. In this circumstance you should > apply a power function with an exponent of about 1⁄ 1.1 or 1⁄ 1.2 to > correct for your bright surround." -- there must be more maths here. Formerly, no, there isn't a whole lot of maths, since it's all based on Psychometric measurements. See Giorgianni & Madden's "Digital Color Management, Encoding Solutions" to get the flavour of this, while Mark Fairchild's "Color Appearance Models" has a more current representation of the basis on which this this type of adjustment can be made. I'm sure there's lot of underlying data in various books by Hunt too. [I'd imagine the original TV adjustment was made during the development of the technology and standards, "by eye" based on viewing tests. The Color Science basis for the adjustment wouldn't have had to been known by any involved, although the general principles may well have been known for a long time. It appears that the quantification of various such affects was done in the mid 60's by Hunt, Stevens, Bartleson, Breneman etc.] In Argyll's dispcal I've made use of the Psychometrics encoded in CIECAM02 to do the gamma adjustment. It's all kind on moot for color managed applications though. Graeme Gill. ------------------------------------------------------------------------------ Master Visual Studio, SharePoint, SQL, ASP.NET, C# 2012, HTML5, CSS, MVC, Windows 8 Apps, JavaScript and much more. Keep your skills current with LearnDevNow - 3,200 step-by-step video tutorials by Microsoft MVPs and experts. SALE $99.99 this month only -- learn more at: http://p.sf.net/sfu/learnmore_122912 _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
