Originally Posted by darinp2
It looks like that 5% APL pattern you were referring to has 5% of the screen covered by white rectangles. If I were to estimate the value for that image in that calculator I would change the percentage of the screen covered by the checkerboard to 10% (twice the 5% because the checkerboard contains equal amounts of white and black). And I would change the room gain to 0 to just consider the projector. As an example, for something with 800:1 ANSI CR and 6000:1 on/off CR and those other choices, that calculator would estimate the CR in that image at about 3600:1.
Let's try another example, but taking the room into account this time. Let's suppose the room limits ANSI CR on the screen to about 200:1, so the reflectivity value is 0.01.
According to the calculator, a projector with 4000:1 on/off CR and 250:1 ANSI CR would produce 884:1 CR for that pattern.
If we boost the on/off CR to 8000:1 but keep the 250:1 ANSI CR, the pattern's CR would be 982:1, which is an increase of 11%.
Or, instead, if we boost the ANSI CR to 850:1 but keep the 4000:1 on/off CR, the pattern's CR would be 1183:1, which is an increase of 34%.
The 34% increase is about 3 times as much as the 11% increase. Basically, the ANSI CR boost would improve the pattern's CR more than the on/off CR boost would, even though the pattern has a low APL, and even though the room is reflective.
Just for grins, if we boost both at the same time (on/off CR to 8000:1 and ANSI CR to 850:1), the pattern's CR would be 1366:1, which is an increase of 55%.
In addition, even if we boost the on/off CR to infinity but keep the 250:1 ANSI CR, the pattern's CR would be 1105:1, which is still less than what the ANSI CR boost produces.