[FFmpeg-trac] #9085(avcodec:reopened): JPEG: YCCK/CMYK too green (was: JPEG: YCCK too green)
FFmpeg
trac at avcodec.org
Sun Mar 28 21:00:12 EEST 2021
#9085: JPEG: YCCK/CMYK too green
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Reporter: Balling | Owner:
Type: defect | Status: reopened
Priority: normal | Component: avcodec
Version: git-master | Resolution:
Keywords: mjpeg cmyk | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by Balling):
BTW, I found YCCK with inverted colors as promised. Extracted from PDF
with poppler's
{{{
pdfimages -all
}}}
There is an "open" issue in poppler:
https://gitlab.freedesktop.org/cairo/cairo/-/issues/156
So, pdf uses "/Decode [ 1 0 1 0 1 0 1 0 ]" to signal not normal K
component.
The images should look like here on the cover: https://www.amazon.com
/Lewins-CELLS-George-Plopper-ebook/dp/B00JKPGLEA
There is nothing in APP14 that can show that, unfortunately, I though it
should be flags1, but nope. Sigh. Acrobat extracts them by converting to
YCbCr.
You know where to find a pdf ebook, right? D:)
You know I think it is just wrong sRGB conversion if it is what FFmpeg is
targeting. See: https://graphicdesign.stackexchange.com/questions/130658
/conversion-from-cmyk-to-rgb-everything-becomes-greener-sometimes?rq=1 and
https://graphicdesign.stackexchange.com/questions/61294/why-do-
professional-print-houses-use-gamut-limiting-cmyk
As always download and open in normal viewer. I also renaming the issue
since that sample is just CMYK.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/9085#comment:24>
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