richard@gryphon.CTS.COM (Richard Sexton) (11/06/87)
Remember a while back when sombody noticed that adding green to a color mix seemed to increase the flicker ? I mentioned that this was because the green was the quickest or shortest persistence phosphor. George R said: wrong. George was indeed right, but that didn't explain why my (Sony) monitor seemed to more of a flicker problem with green than red or blue. So I asked the question, and cross posted it to comp.graphics, where the answer just popped up, so I scarfed it up, and here it is: In article <880001@hpcehfe.HP.COM> Joyce E. Farrell writes: > >The general rule is that if two phosphors are matched for persistence, >the phosphor that will be more likely to cause flicker will be the >brighter of the two. If two phosphors are matched for persistence and >luminance, they will be equally likely to appear to flicker. >The red, green and blue phosphors have relatively short persistences and >are not that different in their phosphor decay rates. >I am guessing therefore, that your green phosphor was brighter than >your red and blue. You may have sent the same DAC values (or voltage >values to the electron guns), but green would appear to be brighter >because of the fact that people are more sensitive to wavelengths >corresponding to "green" >(i.e. if you look at the photopic sensitivity function >that describes how sensitive we are to wavelengths in the visible range >you will see that the function peaks at a wavelength corresponding to green) >I am guessing that if you were to measure the luminance of the green, red >and blue images (with a photometer), the green image that appeared >to flicker would be the brightest. Makes sense to me. I think now, in retrospect that what I must have read about the Sony green phosphor was that it was the brightest. Which would have made it flicker more. Dammit, I read *something* about that green phosphor. Oh, well, moot point. The boys are back from Comdex and said the scan doubler looks *real* sweet. Spoils you, in fact. :-( -- Richard J. Sexton INTERNET: richard@gryphon.CTS.COM UUCP: {hplabs!hp-sdd, sdcsvax, ihnp4, nosc}!crash!gryphon!richard "It's too dark to put the keys in my ignition..."