[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
------------------------------------+------------------------------------
             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           |
------------------------------------+------------------------------------

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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