Bug 688543

Summary:	Gray lines appearing in PDF 1.6 transparent file
Product:	Ghostscript	Reporter:	Raph Levien <raph.levien>
Component:	Color	Assignee:	Ralph Giles <ralph.giles>
Status:	NOTIFIED FIXED
Severity:	normal
Priority:	P2
Version:	master
Hardware:	All
OS:	All
Customer:	190	Word Size:	---

Description Raph Levien 2006-02-07 09:03:31 UTC

Ghostscript (8.53) has a little problem to rasterize the attached file
(kake-INFORMEX.pdf), with tiff32nc as output driver:

- At 72 dpi,  there is a thin horizontal grey line just above the text
"Supersep systems offer numerous benefits", which shouldn't be there
(it's not visible with Acrobat 7 or any other reader I've tried)

- At 100 dpi, again tiff32nc, the horizontal line disappears, but there
is another one, vertical, on the left of the image.

At other resolutions, you can have the line on the right or on the top
of the image, or both, or all of them, it's completely random.

Comment 1 Raph Levien 2006-02-07 09:05:29 UTC

Created attachment 2004 [details]
test file kake-INFORMEX.pdf

Comment 2 Marcos H. Woehrmann 2007-03-02 13:31:04 UTC

At 100 DPI I don't see the lines with 8.51 and 853 but do with 8.54 and head.

Comment 3 Marcos H. Woehrmann 2007-03-05 13:08:00 UTC

It appears that the following change which happend in r6180 is responsible for the spurious lines:

*** ztrans.c    Mon Oct  3 23:30:02 2005
--- ../../gs.6180/src/ztrans.c  Tue Nov 15 05:27:17 2005
***************
*** 274,280 ****
      else if (code > 0)
        params.Background_components = code;
      if ((code = dict_floats_param(imemory, dop, "GrayBackground", 
!                   1, params.Background, NULL)) < 0
        )
        return code;
      if (dict_find_string(dop, "TransferFunction", &pparam) >0) {
--- 274,280 ----
      else if (code > 0)
        params.Background_components = code;
      if ((code = dict_floats_param(imemory, dop, "GrayBackground", 
!                   1, &params.GrayBackground, NULL)) < 0
        )
        return code;
      if (dict_find_string(dop, "TransferFunction", &pparam) >0) {

Comment 4 Ray Johnston 2007-04-12 11:54:43 UTC

Adjusting priority to reflect that this is a customer bug.

Comment 5 Timothy Osborn 2007-05-07 10:44:19 UTC

Fixed in rev. 7904 by changing the rounding method applied to the transparency
group bounding box to use the same "Center-of-pixel Filling Rule" that is
applied to images.

Comment 6 Ray Johnston 2007-07-24 22:13:31 UTC

A better fix for this is being tested. In the meantime, re-open this bug.

Comment 7 Henry Stiles 2008-05-07 16:30:13 UTC

> A better fix for this is being tested. In the meantime, re-open this bug.

This was written 10 months ago and nothing followed.  Reassigning to the color
group.  Let me know if this is an incorrect assignment.

Comment 8 Ralph Giles 2008-05-20 16:18:08 UTC

The issue seems resolved, whether Tim's better fix was committed or not. Closing
as resolved.