Originally Posted by Jim McC
When I set the contrast with your test pattern, I come up with 18(out of 30). When I use the S&M disc, I get 8(out of 30). What do you suggest? How do I know what's right?
If you start with contrast set to maximum there are a number of factors that might suggest turning down contrast. You don't really comment on what criteria is suggesting that you set contrast lower using the Spears & Munsil disc. Basically to comment I have to take a wild stab at it.
I have not used the Spears & Munsil disc. I have only read some of the writing related to their disc, such as the comments on contrast. Since I do not have a copy I cannot be sure, but I think their patterns may go above reference white. My best guess is that their criteria might suggest to calibrate for maximum white (254), rather than reference white (235). If you try to optimize for maximum white (254), sure the contrast setting would be lower than if you choose to optimize for reference white (235).
Personally I don't see much reason to retain information above reference white (235) at the display, unless a high contrast setting has a detrimental effect below reference white on a particular TV. My general recommendation to allow 244 gray to flash is because some displays have a few negative effects near where white runs out, and the recommendation is intended to be conservative to try to avoid negative effects going below reference white. Based on the results in http://www.avsforum.com/avs-vb/showt...3#post18425133
and my own looks at video levels from random commercial video I don't have any common examples of real information above reference white, so generally I think it makes sense to calibrate for reference white (235), rather than maximum white (254). The recommendations from the AVS HD 709 Patterns Manual are simply intended to apply to as many different displays as possible, without being overly dense.