FW: [Tig] D-Cinema Suite contd.

Richard Dean rdean54
Sun Mar 9 02:27:41 GMT 2003


I agree that in some monitors a black level can shift due to various levels
of APL and the devices ability (or inability) to properly render bright to
dark transitions. However in designing THX Optimizer, to help with home
theater system performance on THX certified DVD's, a brightness test was
devised to fit a number of home display technologies. Including only the
pluge pattern, one brightness setting was found to be correct, but when
adding a grey to white pattern on top and bottom of the pluge, another
setting was found to be correct. This was across the board in a number of
display devices.

We found that the iris in the eye, responding to brighter images in a
general proximity to shadows, is a player in how shadows are perceived. This
can effect the way a colorist sets black levels for an overall scene. Most
of us have seen this fact when mastering a movie in 2.35, then making
evaluations on a full frame version without the black matt at top and
bottom. It has made some wish to go back and tweak black levels.

This was also evident when specifying a color correction environment for
Digital Cinema. The difference using a 15 foot wide screen and a 25 foot
wide screen (same 12fl brightness on each) will make a difference in
decisions made during grading sessions and the result looking correct on a
regular cinema sized screens. The 25 foot screen was more reliable. This was
found to be due to bright objects on the screen closing down the iris in the
eye. The bigger screen separated the objects away from each other. As DLP
technology was used in these tests, there was no beam regulation or clamping
to blame.

So back to subject; Same monitor size will help and this is assumed. But
with CRT's, after ageing occurs, you cannot always expect the rendering of a
test pattern to be the same as a more complex real image, especially when
detailing the amount of luminance in shadows. While the technology used
today is far more advanced than monitors we used prior, it still is not a
perfect world. Even DLP has a light bulb that ages!

Interesting thread here, look forward to more comments.

I do not work for monitor manufactures, I just have to deal with them.

Rick Dean
THX LTD.







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