The point is the filter calibrated the out of control "native" color profile. The lens also has an effect on reducing light scatter and fluorescent illumination of the darker areas.
My point is I believe I replicated the process they are charging $250.00 for ( They should have just sold me one ) Read the whole tuning thread @ cine4home.de (a very reputable site by the way)
The way I have my projector mounted in a soffit, the lens and hood "plugs" the porthole in the sheet rock.. so I just plugged it at the same angle of the light coming out, ( use text or credits paused in a darkened room to see the beam angle) I see no backscatter at all with the filter in place, 0.
The way I can tell my black floor has changed is on a full black out scene, my eyes do not adjust and it would seem to go fully black. If it were not for the slight bright corners these units have the effect would be even more pronounced.
Now, I have the blackest room I have ever personally been in.... is was designed for zero reflections, zero light contamination, and has light absorbing Duvetyne on all surfaces including the full ceiling, and a jet black carpeted floor. There is nothing in there that is not jet black, my phone backlight can be seen on my screen from 21' away, after your eyes adjust
With this being said I am able to discern this difference like it was made for my setup.
30% (quoted by Cine4Home) lower black level for $28.00 is a home run.
Below shows the improvement from their testing (the 3rd pic is without the filter, the last is with it) My cell pics seem to mirror their results. Unfortunately my EyeOne meter will not report a black level this low I am sure.
This is not new, Guy Kuo was doing this when I joined way back in 1999, (I had to rejoin for some reason in 03)
People have gotten away from this due to all the advances, electronics that can achieve similar results. Just not for $30.00. Plus now we have way more efficient light engines with a surplus of lumens when back then 400 lumens calibrated was good.
With all that being said, the black level and contrast presentation rivals my 65" VT Plasma for sure (considering it is projection)