Based on the measurements I have seen, it appears that various displays and settings primarily operate differently depending on how information is presented to the display, and I do not see a reason that unique measurement patterns are necessarily required for generally comparable gamma measurements on a majority of displays. Certainly if you only want to take a single gamma measurement run it makes sense to carefully consider how to assemble a gamma measurement pattern to meet your intentions, but I see no clear reason to doubt if holding a constant average picture level (APL) and a constant average luminance (AL) during a measurement run provides a single point of comparable gamma information across various displays and settings. Personally I have not measured patterns that only intend to hold a constant average luminance (AL), yet based on the preliminary notes for the upcoming Spears and Munsil disc, it would appear that everyone is not tied to the idea that various displays require dissimilar measurement patterns for gamma.
Some displays can clearly vary relative gray measurements as APL or AL changes, so if APL & AL are constant during the measurement run there are simply fewer variables to possibly influence the reported gamma information on displays that do not provide consistent measurements regardless of pattern.
Primarily I’m just going to discuss the plasma measurements from Chad B (See linked thread). The items he measured that hold a constant APL & AL during the measurement run are listed below from darkest to brightest (See linked PDF for graphs):
- DB Ramp Dark (Darkest image)(4% APL & 3% AL)
- AVS S APL (Dark image)(7% APL & 5% AL)
- Chad B’s APL (Typical image)(19% APL & 13% AL)
- AVS L APL (Bright image)(36% APL & 25% AL)
- DB Ramp Bright (Extremely bright image)(85% APL & 84% AL)
APL and AL - different things
Spears and Munsil -
For the grayscale and gamut patterns, we decided to only include equal energy patterns. Similar in concept to the AVS709 Constant APL patterns.
ramp method - 5%-15% high
16:9 - 0.25%-2.25% square
quadrate - 0.14%-1.27%