[gs-bugs] [Bug 691134] Image missing

bugs.ghostscript.com-bugzilla-daemon at ghostscript.com bugs.ghostscript.com-bugzilla-daemon at ghostscript.com
Tue Feb 23 17:42:19 UTC 2010


ray.johnston at artifex.com changed:

           What    |Removed                     |Added
             Status|NEW                         |RESOLVED
           Priority|P2                          |P4
         Resolution|                            |WORKSFORME

------- Additional Comments From ray.johnston at artifex.com  2010-02-23 09:42 -------
The tiffsep device implements 'overprint', while the 'display' device and the
'tiff32nc' devices do not If painting is done in some 'separation' color,
overprint is effectively ignored since ONLY the tiffsep device maintains the
separations. Otherwise we use the 'tint transform' and paint as if overprint
is false (normal PS painting that replaces the colors on all planes).

This behavior is what you get from Acrobat when the Overprint setting is
'Never' (Acrobat 9 -- different settings in older Acrobat versions).

Since gs works the same as Acrobat 9 when Overprint preview is off, closing
as 'WORKSFORME' (works as expected). To see overprint, one must use a device
that supports separations such as the tiffsep of psdcmyk device. I checked
that the psd image looks OK as well as the composite CMYK created by the
tiffsep device (created FROM the C, M, Y, K, and Pantone 7503 separations).


Detailed analysis...

The first image I see painted in the problem area is: Im9 Do
This image is defined in object 14 as:
%Resolving: [14 0]
<< /Type /XObject /Subtype /Image /Width 994 /Height 995 /BitsPerComponent 8
/ColorSpace /DeviceCMYK /Length 265179 /Filter /DCTDecode >>

The image is then erased later by: Im10 Do
Im10 is defined in object 15 as:
%Resolving: [15 0]
<< /Type /XObject /Subtype /Image /Width 994 /Height 995 /BitsPerComponent 8
/ColorSpace 52 0 R /Length 14000 /Filter /DCTDecode >> 

And the ColorSpace in object 52 is:
%Resolving: [52 0]
[ /Separation /PANTONE 7503 C /DeviceCMYK 55 0 R ]

Since the data for the image is all 0's (white in CMYK) it paints white,
effectively erasing the underlying image.

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