Re: Colorsync-users Digest, Vol 3, Issue 219
Re: Colorsync-users Digest, Vol 3, Issue 219
- Subject: Re: Colorsync-users Digest, Vol 3, Issue 219
- From: email@hidden
- Date: Thu, 22 Jun 2006 14:18:32 +0200
But that's the entire point of the exercise; the processing pipeline
BEFORE the videolut can be of high enough precision. It used to be
that the video lut and video pipeline incure the most loss. So you
want to calibrate the video lut to something that is close to a
native response, but preferably allows:
- a gray response for equal RGB values, so that non-colormanaged
elements at least appear neutral.
- a gamma curve value (as opposed to a lut) in the corresponding
profile.
Fortunately, video card these days allow larger than 8bit video luts
and will actually do something smart with it such as temporal
dithering to bypass the 8bit monitor connection. This largely
eliminates the need for fancy curves.
In addition, the L curve as found in Lab, only has a remote relation
to perception for a reference of 100cd/m2 and 256 discrete steps.
Which is probably fine for most prepress environments. I fail to see
the usefulness for all other situations where current LCDs can easily
do anything from 250cd/m2 upto 1000cd/m2. More to the point, I fail
to see the usefulness of patenting calibration to a particular curve
as if that is a novel idea and as if they actual did all the hard
work to come up with that curve to begin with...
And with all due respect, but where do you get the notion that there
is some kind of remote relation between sRGB gamma 2.2 and the L*
curve? Following is verbatim from the w3 website about sRGB gamma:
"The effect of the above equations is to closely fit a
straightforward gamma 2.2 curve with an slight offset to allow for
invertability in integer math."
Which simply shows a remarkable lack of understanding on their side
about integer math, and which is why we end up with a lut based gamma
version of sRGB, while current systems (and the actual image data)
simply where meant to respond according to the normal gamma value.
Regards,
Oscar
On Jun 22, 2006, at 13:19 PM, Karl Koch wrote:
visual system i.e. L* and then on to a monitor that is calibrated
to the same tonal response curve. This results in zero loss, not
counting the loss in the LUTs.
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Colorsync-users mailing list (email@hidden)
Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden