Comments by iashdown (Top 1 by date)

Close but no cigar -- the grayscale conversion equation should be:

GRAY = 0.2125 * RED + 0.7154 * GREEN + 0.0721 * BLUE

to comply with ITU-R Recommendation BT.709, "Basic Parameter Values for the Studio and for International Programme Exchnage." This standard defines the chromaticities (colors) of virtually all modern color display monitors.

The constants presented in this article are for NTSC CRT phosphors, which have been out of date for decades.