Originally Posted by PlasmaPZ80U
Regarding the APL Large and Small Gray Patterns, if you were to quantify the APL that each of these holds constant, what would that be? Basically, what would the equivalent percent stimulus for a full field pattern for each?
It depends how you want to try to make an approximation. Just averaging the video levels doesn't make sense, because a white window clearly puts a lot more strain on plasma or CRT than a field of the same average. What I mean is that a 100% gray (reference white) window at 15% area would average to 15% gray, and I don't think many would argue that a white window is more difficult for plasma or CRT to produce than a 15% gray field. Probably a more reasonable thing to do is to gamma-adjust video levels before averaging, since in effect that's what the TV has to do with the light output. The 15% area white window would still have a gamma-adjusted average of 15%, but the matching field after a 2.2 gamma adjustment would be around a 42% gray field (.42^2.2~15%).
If I put a single-point curve adjustment on the image to approximate 2.2 gamma, here are the results:
Small APL -> gamma-adjusted average around 4.7%, which would be similar to a 25% gray field (.25^2.2~4.7%)
Large APL -> gamma-adjusted average around 24.7%, which would be similar to a 53% gray field (.53^2.2~24.7%)
As examples of random somewhat bright images (white in uniforms), here was the current headline from NFL.com http://www.nfl.com/news/story/09000d...P11_cp#photo=1
If I convert the images to black and white and then follow the same procedure, here are the results:
Image 1 -> gamma-adjusted average around 17.6%
Image 2 -> gamma-adjusted average around 23.5%
Image 3 -> gamma-adjusted average around 21.6%
Image 4 -> gamma-adjusted average around 12.9%
For examples of random movie images, the Blu-ray posts from the Star Wars http://www.avsforum.com/avs-vb/showt...6#post20965206
Post #3 -> gamma-adjusted average around 15.7%
Post #4 -> gamma-adjusted average around 21.6%
Posts #5 & #6 -> gamma-adjusted average around 2.4%