Elle Stone wrote: > Why do some references give that second set of values? Is there a reason > to prefer x=0.3127, y=0.3291 to the more commonly quoted x=0.3127, y=0.3290?
I don't have a specific answer, but you will note that the x,y numbers are rounded to 4 digits, which seems to be for practical calculation reasons, as well as notions of excessive meaningless precision. Things that add uncertainty to D65 values: Very slight change in the CIE standard observer definition from 1931 to current standards. Whether the D65 spectrum is from the Daylight equation or the specific D65 distribution (they are not quite the same). How the CIE calculation dealt with the 5nm spacing of the D65 spectrum - ie. whether it computed the integration at 5nm (which is permitted by the CIE standard), or whether it up samples to 1nm (which is encouraged by the standard). Whether the CIE x,y tables were used instead. Whether the Daylight x,y chromaticity coordinate equation was used instead of the spectral calculation or table values. Round any one of these up and you may get a different number. Graeme Gill. ------------------------------------------------------------------------------ Managing the Performance of Cloud-Based Applications Take advantage of what the Cloud has to offer - Avoid Common Pitfalls. Read the Whitepaper. http://pubads.g.doubleclick.net/gampad/clk?id=121051231&iu=/4140/ostg.clktrk _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
