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clipka <ano### [at] anonymous org> wrote:
> Warp schrieb:
> > Some brief history of why gamma correction exists in the first place
> > (going all the way back to the invention of CRT) and where the name "gamma"
> > comes from could be an interesting tidbit of information. This doesn't need
> > to be long. One single paragraph should be enough.
> Um... that information is in there already... so you got bored, hm? ;-)
IIRC gamma correction started from the dawn of television and is related
to how a TV camera and a CRT works.
--
- Warp
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Warp schrieb:
>>> Some brief history of why gamma correction exists in the first place
>>> (going all the way back to the invention of CRT) and where the name "gamma"
>>> comes from could be an interesting tidbit of information. This doesn't need
>>> to be long. One single paragraph should be enough.
>
>> Um... that information is in there already... so you got bored, hm? ;-)
>
> IIRC gamma correction started from the dawn of television and is related
> to how a TV camera and a CRT works.
Ah, I get your point now.
No, I don't think I want to do a concise essay about gamma in image
processing in general. I'll leave that up to Wikipedia. I'm more in for
the facts pertaining to /digital/ image processing.
Yes, gamma pre-correction in TV broadcasting predates gamma
pre-correction in computers.
No, the one is not the reason for the other; rather, both share a common
reason: It simplifies driving the CRT.
I don't think the first CRTs used for computer displays were full TV
sets, as this would have required a HF modulator in the display adaptor
to drive the TV set's antenna input; more or less directly driving the
CRT would have required a much simpler hardware. So I guess the way TV
images were transmitted over the air was probably irrelevant for the
decision to gamma pre-correct computers' display output.
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On 26.03.2010 22:04, clipka wrote:
> Comments appreciated.
Makes a good reading. And I do not agree with the reordering suggestions
but hey, it is a wiki article and everyone who wants to improve it can
do so.
What I do miss for the "Why should I care" section is the mentioning of
all the include files that are shipped with POV-Ray and have color
definitions within them (colors.inc, woods.inc, metals.inc ... ). All of
them do use gamma pre-corrected color definitions and are pretty useless
for 3.7 as they are now.
And the headline "Why Does POV-Ray Not Do It The Photoshop Way?" does
mostly show that you do not have a good idea of what (contemporary
versions) of P'shop are doing as most operations there are internally
done in linear color space and it is also fairly easy to setup the
P'shop color picker to show linear color values and not perceptual ones.
-Ive
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Am 28.03.2010 11:28, schrieb Ive:
> Makes a good reading. And I do not agree with the reordering suggestions
> but hey, it is a wiki article and everyone who wants to improve it can
> do so.
Yes. Well, at least as soon as the page moves from my own personal space
to some more official location.
> What I do miss for the "Why should I care" section is the mentioning of
> all the include files that are shipped with POV-Ray and have color
> definitions within them (colors.inc, woods.inc, metals.inc ... ). All of
> them do use gamma pre-corrected color definitions and are pretty useless
> for 3.7 as they are now.
That's a good point.
However, I think the proper approach for those would be to fix them by
virtue of an "#if (version >= 3.7)" statement (or, maybe even better
yet, pre-definition of macros as suggested by the article).
(I think the materials need rework anyway, to allow for better
interoperability with radiosity.)
Still, yes, even then the article should possibly mention the topic of
legacy scenes in general.
> And the headline "Why Does POV-Ray Not Do It The Photoshop Way?" does
> mostly show that you do not have a good idea of what (contemporary
> versions) of P'shop are doing as most operations there are internally
> done in linear color space and it is also fairly easy to setup the
> P'shop color picker to show linear color values and not perceptual ones.
With "The Photoshop Way" I intended to refer to what you get when you
use the color picking tool of image editing software in general (taking
Photoshop just as a popular example) - with gamma pre-corrected values
probably still being the default (I still have an older value of
Photoshop, so I might be wrong there). And as the internals are hidden
from the casual user anyway, I don't think many users would associate
that title with those inner workings.
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