[Poppler-bugs] [Bug 47706] Exporting pdf from LibreOffice with smooth gradient displays striped in Evince, shows correctly in Adobe Reader

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=47706

--- Comment #6 from James Cloos <cloos at jhcloos.com> 2012-03-23 17:17:42 PDT ---
> This is not quite the same as the LibreOffice PDF. The LibreOffice PDF is
> emulating a gradient by drawing series of rectangles.

Oh.  I didn't look at it because the symtoms seemed to match those of a
native shading.

> XYZsweep contains a native PDF gradient.

Yes.

> The seams in the cairo rendering of XYZsweep have been
> fixed with the release of cairo 1.12 which supports Type 6/7 gradients.

I've been using git master for cairo and poppler for months (years?).

> XYZsweep.pdf is an interesting test case.

I wrote the postscript version to see what ghostscript would do after
the colour management features were added.

> Cairo (using cairo 1.12 and poppler master) renders this almost the
> same as acroread while splash renders it similar to ghostscript with a
> much larger pink area in the bottom right.

GS and poppler both use lcms2.  When rendering to RGB both default to sRGB.

Here, acro's on-screen rendering looks like mupdf's, which does a simple
lab->srgb conversion.

But I get the same result from evince and poppler-glib-demo as I get
from splash and gs.  (but with the white curves between the patches.)

> I'm not sure which is correct.

Neither do I.

> Printing the file as a PDF to my printer
> (I don't know who makes the PDF interpreter for Xerox printers)

Depends on the printer.  Xerox licenses Adobe's for their more expensive
printers, but use someone elses for the less costly ones.  If your
printer supports pantone directly (ie as /DeviceN named colours) then it
probably has adobe's ps3/pdf1.7 interpreter.  Otherwise it probably has
the alternate ps3/pdf1.5.

> results in the same output as acroread.

> After printing the file to PS using acroread, ghostscript still
> renders it the same with the larger pink area but my printer (Adobe PS
> interpreter) gets it wrong with large blob of dark blue on the bottom
> right.

Interesting.  If I set 'let the printer handle colors' in the advanced
dialog from acro's print dialog, gs generates the same rendering as it
does with the original pdf.  If that is unset, it generates a subdued
rendering similar to acro and mupdf.

The first case creates a CIEBasedABC colour space in the ps, so that is
expected.  The latter uses /DeviceCMYK (which is why gs renders it a bit
subdued as compared to /DeviceRGB).

The acro rendering probably is correct.

I’ll have to spend the toner and see what my printer does.

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