Ghostscript tiffsep creates CMYK image that is inverted in ImageMagick display? (repost)

[sdaau]

Just posted this: http://stackoverflow.com/questions/4332 ... ck-display, thought it might be a good idea to repost here, as this could be a bug with `display`:

Not sure what to make of this - but let's say we work with this PDF file: https://stlab.adobe.com/wiki/index.php/File:Test.pdf, and I want to obtain separations using Ghostscript's `tiffsep` device:

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    cd /tmp
    wget https://stlab.adobe.com/wiki/images/d/d3/Test.pdf
    ghostscript -q -sDEVICE=tiffsep -dNOPAUSE -dBATCH -dSAFER -r72x72 -sOutputFile=testseps.tif -dFirstPage=1 -dLastPage=1 Test.pdf
    eog testseps.tif & display testseps.tif

This generates five files: `testseps(Black).tif`, `testseps(Cyan).tif`, `testseps(Magenta).tif`, `testseps.tif`, `testseps(Yellow).tif`. I open the full-color output (`testseps.tif`) in both Eye of Gnome (`eog`), and ImageMagick's `display`, and this is what I get (Ubuntu 14.04, MATE desktop, ghostscript 9.10, ImageMagick 6.7.7-10 2017-03-14 Q16):



Namely, ImageMagick's `display` (left) shows this file with inverted colors, while Eye of Gnome (right) shows the very same file correctly?!

So how can I get this CMYK tiff to show correctly in both `display` and Eye of Gnome? Can I somehow convert it with ImageMagick's `convert`, and what would the command line be? I've already tried something like:

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    convert testseps.tif -colorspace CMYK -alpha off -define quantum:polarity=min-is-white -colorspace CMYK testseps2.tif

... and that file again shows the same problem.

EDIT: Also, if I try to combine the individual separations using `convert`:

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    convert \
    testseps\(Cyan\).tif \
    testseps\(Magenta\).tif \
    testseps\(Yellow\).tif \
    testseps\(Black\).tif \
    -set colorspace CMYK \
    -profile /usr/share/ghostscript/9.10/iccprofiles/default_cmyk.icc 
    -combine 
    combined.tif

... then `combined.tif` shows properly in ImageMagick `display` - but is shown as completely black in Eye of Gnome! If I add the `-negate` switch after `-combine`, then I'm back to the previous state (`display` shows inverted, `eog` shows correct)

EDIT2: Tried to use a service http://www.rgb2cmyk.org/, to obtain a CMYK tif of the RGB screenshot posted here, and that one also shows the same bug: it is inverted in `display`, and shown correctly in Eye of Gnome.

Just for reference, here is a bit of info about `testseps.tif`:

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    $ tiffinfo testseps.tif 
    TIFF Directory at offset 0x8 (8)
      Subfile Type: multi-page document (2 = 0x2)
      Image Width: 612 Image Length: 792
      Resolution: 72, 72 pixels/inch
      Bits/Sample: 8
      Compression Scheme: LZW
      Photometric Interpretation: separated
      FillOrder: msb-to-lsb
      Orientation: row 0 top, col 0 lhs
      Samples/Pixel: 4
      Rows/Strip: 428
      Planar Configuration: single image plane
      Page Number: 0-0
      Software: GPL Ghostscript 9.10
      DateTime: 2017:04:10 12:53:45
      ICC Profile: <present>, 56412 bytes
    $ identify -verbose testseps.tif 
    Image: testseps.tif
      Format: TIFF (Tagged Image File Format)
      Class: DirectClass
      Geometry: 612x792+0+0
      Resolution: 72x72
      Print size: 8.5x11
      Units: PixelsPerInch
      Type: ColorSeparation
      Endianess: MSB
      Colorspace: CMYK
      Depth: 8-bit
      Channel depth:
        cyan: 8-bit
        magenta: 8-bit
        yellow: 8-bit
        black: 8-bit
      Channel statistics:
        Cyan:
          min: 0 (0)
          max: 235 (0.921569)
          mean: 5.93515 (0.0232751)
          standard deviation: 33.3466 (0.130771)
          kurtosis: 28.8423
          skewness: 5.53334
        Magenta:
          min: 0 (0)
          max: 245 (0.960784)
          mean: 2.7823 (0.010911)
          standard deviation: 18.73 (0.0734511)
          kurtosis: 68.8725
          skewness: 8.12072
        Yellow:
          min: 0 (0)
          max: 255 (1)
          mean: 5.04176 (0.0197716)
          standard deviation: 30.8529 (0.120992)
          kurtosis: 34.9211
          skewness: 6.05297
        Black:
          min: 0 (0)
          max: 226 (0.886275)
          mean: 1.06569 (0.00417917)
          standard deviation: 13.7509 (0.0539252)
          kurtosis: 227.454
          skewness: 15.0002
      Image statistics:
        Overall:
          min: 0 (0)
          max: 255 (1)
          mean: 3.70622 (0.0145342)
          standard deviation: 25.5137 (0.100054)
          kurtosis: 51.8946
          skewness: 7.28691
      Total ink density: 298%
      Rendering intent: Undefined
      Gamma: 1
      Interlace: None
      Background color: cmyk(255,255,255,0)
      Border color: cmyk(223,223,223,0)
      Matte color: cmyk(189,189,189,0)
      Transparent color: cmyk(0,0,0,0)
      Compose: Over
      Page geometry: 612x792+0+0
      Dispose: Undefined
      Iterations: 0
      Compression: LZW
      Orientation: TopLeft
      Properties:
        date:create: 2017-04-10T12:53:45+02:00
        date:modify: 2017-04-10T12:53:45+02:00
        signature: 1ad1532f697fa72492fe994d79f1b67d617a34cd927f31b41e6a12214b9bc49e
        tiff:endian: lsb
        tiff:photometric: separated
        tiff:rows-per-strip: 428
        tiff:software: GPL Ghostscript 9.10
        tiff:timestamp: 2017:04:10 12:53:45
      Profiles:
        Profile-icc: 187484 bytes
          Description: Artifex CMYK SWOP Profile
          Manufacturer: Artifex CMYK SWOP Profile
          Model: Artifex CMYK SWOP Profile
          Copyright: Copyright Artifex Software 2011
      Artifacts:
        filename: testseps.tif
        verbose: true
      Tainted: True
      Filesize: 220KB
      Number pixels: 485K
      Pixels per second: 24.24MB
      User time: 0.020u
      Elapsed time: 0:01.019
      Version: ImageMagick 6.7.7-10 2017-03-14 Q16 http://www.imagemagick.org

[snibgo]

You are using a very very old version of IM (v6.7.7-10). I suggest you upgrade. Does that cure the problem?

[sdaau]

Thanks @snibgo - I installed ImageMagick-7.0.5-4-Q16-x86-static.exe through wine, and ran:

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wine imdisplay.exe

... on the very same file shown earlier, and the result is fine:



So I guess there was a bug in `display` that has since been fixed...