Re: contrast

From: Jeff Kreines (email suppressed)
Date: Wed Jul 12 2006 - 10:28:12 PDT

On Jul 12, 2006, at 9:56 AM, david tetzlaff wrote:

> The meaning of the terms 'contrast' and 'contrast range' are well
> established in the history of photography, and are inverse to one
> another.

But video has a way of stealing, subverting, and re-defining film
terms -- like "gamma" and even "filming" -- all mean different things
in the video/digital world.

However, in projectors and monitors, it's important to have both a
great dynamic range (contrast range in videospeak) with adequate bit
depth (to avoid banding and posterization) as well as good, solid
blacks -- not a milky gray. I have HP 2335 monitors on my computers,
1920 x 1080, and a bargain compared to others, and they are fine for
computer use. When I feed in an HD signal from my cable box (via
component HD) it looks great UNTIL there's a dark scene -- then the
HP's lack of a decent black really is apparent..

Note that this being an LCD screen means it shares some of the LCD
problems. Note that an LCD is used to attenuate the light coming
from a fixed backlight -- polarizers play a part in this, especially
in projectors, but it can be hard for many LCDs to attenuate all the
light -- so unless you greatly reduce brightness, you get milky blacks.

DLPs and LCOS and D-ILA and SXRD are all reflective devices, not in-
line attenuators like LCDs -- so different principles apply. DLPs
divert unwanted light at an angle, and in properly designed systems,
with the new "dark chips" -- you can get very good blacks. The other
devices are all non-mechanical flat silicon chips, that look like a
microscopic display when illuminated -- and contrast depends on the
chip's abilities and optical design. Most new designs for DLP and
LCOS-type chips include an iris -- some manual, some automatic but
can be disabled -- to optimize brightness and black levels and in
automatic mode greatly increase dynamic range.

While I love film projection, I think that 16mm projection is going
to disappear, because 16mm prints are beginning to disappear, and
outside of archives and schools, there's not a lot of new 16mm
installations. While this is sad, it might be that good HD
projection will be superior to mediocre (face it, a lot of it is)
16mm projection. (Great 16mm projection is still a glorious thing,
despite the awful optical tracks).

I can imagine new ways of distributing work to new venues that could
be quite interesting, and reinvigorate what was once a large group of
16mm venues. (Remember the Filmmaker's Travel Sheet out of Pittsburgh?)

Jeff "always too contrasty until I mellowed out" Kreines

For info on FrameWorks, contact Pip Chodorov at <email suppressed>.