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<div class="moz-cite-prefix">Den 15.09.2024 19:01, skrev Andrew
Randrianasulu:<br>
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<blockquote type="cite"
cite="mid:CA+rFky5HoMsFzap2oVGCmJr3=45KazCfWDR_TTisUp58YVprQw@mail.gmail.com">
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On Sun, Sep 15, 2024 at 7:41 PM Terje J. Hanssen via Cin <<a
href="mailto:cin@lists.cinelerra-gg.org"
moz-do-not-send="true" class="moz-txt-link-freetext">cin@lists.cinelerra-gg.org</a>>
wrote:<br>
><br>
><br>
><br>
> Den 15.09.2024 18:02, skrev Andrew Randrianasulu via Cin:<br>
> > On Sat, Sep 14, 2024 at 1:08 PM Andrea paz via Cin<br>
> > <<a href="mailto:cin@lists.cinelerra-gg.org"
moz-do-not-send="true" class="moz-txt-link-freetext">cin@lists.cinelerra-gg.org</a>>
wrote:<br>
> >> Sorry Phyllis, I have tried to follow the various
posts about ffmpeg<br>
> >> color problems, but I can't figure out how it
works. I get the<br>
> >> impression that even the ffmpeg developers are not
clear on how to<br>
> >> handle color in their program. I tried reading
Poynton's excellent<br>
> >> book, recommended by Andrew, a couple of years ago
but stopped early<br>
> >> because it was beyond my capabilities.<br>
> > there is simpler colorful intro from around 2006<br>
> ><br>
> > <a
href="https://tech.ebu.ch/docs/techreview/trev_301-gierlinger.pdf"
moz-do-not-send="true" class="moz-txt-link-freetext">https://tech.ebu.ch/docs/techreview/trev_301-gierlinger.pdf</a><br>
> ><br>
> ><br>
> >> There are too many variables, beyond the problems
of ffmpeg: lack of<br>
> >> color management (which I think all reduces to an
initial transcode to<br>
> >> the absolute X,Y,Z color space from which then the
program could do<br>
> >> all the transformations it needs without too much
loss of color info),<br>
> >> lack of support for ICC profiles, not knowing how
each and every<br>
> >> function and plugin of CinGG treats colors,
interaction between CinGG<br>
> >> and ffmpeg, and who knows what else. As Adam said,
“There is no color<br>
> >> management workflow.” It is no coincidence that
colorimetry in editing<br>
> >> programs is found only in the big, rich,
specialized companies.<br>
> >> --<br>
> >> Cin mailing list<br>
> >> <a href="mailto:Cin@lists.cinelerra-gg.org"
moz-do-not-send="true" class="moz-txt-link-freetext">Cin@lists.cinelerra-gg.org</a><br>
> >> <a
href="https://lists.cinelerra-gg.org/mailman/listinfo/cin"
moz-do-not-send="true" class="moz-txt-link-freetext">https://lists.cinelerra-gg.org/mailman/listinfo/cin</a><br>
><br>
> Just in case something here is not already found:<br>
> <a href="https://trac.ffmpeg.org/wiki/colorspace"
moz-do-not-send="true" class="moz-txt-link-freetext">https://trac.ffmpeg.org/wiki/colorspace</a><br>
> <a
href="https://medium.com/invideo-io/talking-about-colorspaces-and-ffmpeg-f6d0b037cc2f"
moz-do-not-send="true" class="moz-txt-link-freetext">https://medium.com/invideo-io/talking-about-colorspaces-and-ffmpeg-f6d0b037cc2f</a><br>
> <a
href="https://kdenlive.org/en/project/color-hell-ffmpeg-transcoding-and-preserving-bt-601/"
moz-do-not-send="true" class="moz-txt-link-freetext">https://kdenlive.org/en/project/color-hell-ffmpeg-transcoding-and-preserving-bt-601/</a><br>
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<br>
In short, the second url above shows how to keep BT.709 (for
HD-video) during transcoding with ffmpeg,<br>
while the the third url keeps BT.601 (for SD-video) <br>
<br>
The second url also has references to additional reading in two
articles, part 1 and 2 (here the English editions):<br>
<br>
*What are Color Models? | Wiggle pixel
<br>
<a class="moz-txt-link-freetext"
href="https://www.wigglepixel.nl/en/blog/what-are-color-models">https://www.wigglepixel.nl/en/blog/what-are-color-models</a>
<br>
<br>
*What are Color Spaces, Color Profiles and Gamma-Correct?
<br>
<a class="moz-txt-link-freetext"
href="https://www.wigglepixel.nl/en/blog/what-are-color-spaces-color-profiles-and-gamma-correction">https://www.wigglepixel.nl/en/blog/what-are-color-spaces-color-profiles-and-gamma-correction</a>
<br>
<br>
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<blockquote type="cite"
cite="mid:CA+rFky5HoMsFzap2oVGCmJr3=45KazCfWDR_TTisUp58YVprQw@mail.gmail.com">
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In this specific case I found following sentence helpful^<br>
<br>
========<br>
<br>
n 1928, the mineralogist<br>
Siegfried Rösch described a<br>
body (Fig. 6), whose surface<br>
is constructed of optimum<br>
colours. Optimum colours<br>
are those among the colours<br>
(trichromatic), which are the<br>
brightest of the same chro-<br>
maticity and the most satu-<br>
rated of the same brightness.<br>
The base of this body is the<br>
diagram published by the CIE<br>
in 1931. It was constructed<br>
as the result of expansive<br>
tests with emmetropes. This<br>
diagram enables calculation<br>
of the position of every colour in relation to its primary<br>
colour. <b>This two-dimensional diagram is only valid for one<br>
respective colour temperature,</b> and it is a section of a<br>
funnel-shaped body (Fig. 7)<br>
<div><br>
</div>
<div>=====</div>
<div>bold by me.</div>
<div><br>
</div>
<div>I do not think I've encountered this bit of info/history
before.<br>
</div>
<div><br>
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><br>
><br>
> --<br>
> Cin mailing list<br>
> <a href="mailto:Cin@lists.cinelerra-gg.org"
moz-do-not-send="true" class="moz-txt-link-freetext">Cin@lists.cinelerra-gg.org</a><br>
> <a
href="https://lists.cinelerra-gg.org/mailman/listinfo/cin"
moz-do-not-send="true" class="moz-txt-link-freetext">https://lists.cinelerra-gg.org/mailman/listinfo/cin</a></div>
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