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Re: Are gamma discrepancies relevant?
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Re: Are gamma discrepancies relevant?


  • Subject: Re: Are gamma discrepancies relevant?
  • From: Marco Ugolini <email@hidden>
  • Date: Thu, 02 Apr 2009 22:49:44 -0700
  • Thread-topic: Are gamma discrepancies relevant?

In a message dated 4/2/09 10:35 PM, Klaus Karcher wrote:

> Marco Ugolini wrote:
>> I don't think any of this proves anything much about inherent advantages
>> accruing from the concordance of TRCs between the file and the monitor
>> profile: it only proves that a file will be subjected to the least possible
>> amount of potentially damaging transformations when...it effectively does
>> not undergo any transformations at all! That much I agree with. :-)
>
> So we agree upon the statement that every conversion in 8 bpc leaves its
> marks in the form of banding, missing steps and color shifts.

It creates the possibility of that sort of results, yes.

The *actual* results will vary based on many variables, and banding is not a
*necessary* consequence in each and every instance. Still, it does happen
often enough to be a sizable concern.

> (As the color spaces are not perceptually uniform, some of them are more
> annoying than others.

Meaning just monitor profile spaces, or all color spaces, working spaces
included?

> Along the gray axis we are particularly sensible
> for those quantization artifacts. The larger the differences between the
> encodings, the more artifacts will be visible.) The logical conclusion
> for me is to avoid 8 bit transformations as much as possible, e.g. by
> performing display calibrations or even colorspace conversions with
> higher bit depths inside the monitor, by co-ordinating working- and
> display TRCs -- or by widening the bottleneck of current display interfaces.

Again, I don't think that "co-ordinating working- and display TRCs" does
much to solve the problem, because it's a solution only in the absence of
vcgt curves, which always exist in monitor profiles.

I agree much more strongly on the desirability and usefulness of on-board
high-bit monitor LUTs, or even ... heaven forfend ... high-bit display cards
in the CPU itself!

You may say I'm a dreamer, but I'm not the only one... ;-)

Marco


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  • Follow-Ups:
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      • From: Koch Karl <email@hidden>
References: 
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