Re: Gamma settings for monitors
Re: Gamma settings for monitors
- Subject: Re: Gamma settings for monitors
- From: Roger Breton <email@hidden>
- Date: Wed, 18 Jul 2001 21:28:07 -0400
Thank's Andy for your gamma insights. Yes, I agree with you whe you state
that the television broadcast industry has long settled on a way to
optimally encode video signals in close loop with receivers in homes for
uniform viewing of color images. But the same cannot be said for the desktop
publishing industry. Not yet, I think. The problem stems from the fact that
good and relevant documentation relevant to the Mac is relatively scarce --
not general gamma documentation like REC 709 or NTSC 1953 but exact
implementation details with regards to today's Macintosh G3 and G4 video
card.
What you describe, Andy, is unfortunately true about QuickDraw having its
own gamma, resulting in an overall gamma of 1.8.
And I have to agree with Neil Okamoto when he writes that Macs's gamma are
now in-line with PC's "standard gamma" of 2.2. Because that's the only
conclusion I can draw from my own gamma testings on my blue&white G3
attached to my 900u Mitsubishi monitor. I get the same non-linear
relationship between input RGB and output luminance whether "uncalibrated"
or "2.2 calibrated"! Does this would mean that the 2.2 gamma I observe in an
"uncalibrated" state is the sole result of my monitor's native hardware
gamma?
I wish I could explain this, practically though, because it drives me nuts.
Al least on the Windows side, we know for sure that there is no gamma
correction going on. Period.
Now, whichever gamma we choose to calibrate our monitors to, the debate is
still opened as to the "best" working space gamma in Photoshop! I can safely
say that 2.2 makes midtones and shadows darker and 1.8 makes them lighter.
But that is an issue only when working with legacy files! Or is it? Because,
if you display a Lab image, then, irregardless of calibrated gamma, you get
the same luminance output. The same could be said, I guess, for working with
CMYK images. But what about converting RGB images from a scanner? Do I
convert to 1.8 gamma working space or 2.2 gamma working space? What will
happen?
Roger Breton
Laval (Quibec)
Canada