Bug 19760

Summary:	Horizontal lines appear on blue background on pdf
Product:	poppler	Reporter:	Pedro Villavicencio <pvillavi>
Component:	general	Assignee:	poppler-bugs <poppler-bugs>
Status:	RESOLVED MOVED	QA Contact:
Severity:	normal
Priority:	medium	CC:	madbiologist2016
Version:	unspecified
Hardware:	Other
OS:	All
Whiteboard:
i915 platform:		i915 features:
Attachments:	align fills

Description Pedro Villavicencio 2009-01-27 06:30:14 UTC

this report has been filed here:

https://bugs.edge.launchpad.net/poppler/+bug/318130

"We have a pdf file exported from Open Office Impress. The background is blue and there are horizontal lines through the image. The lines vary somewhat in colour, going from white to the blue.
If the slide show is made in OO Impress, all is well (showing that this isn't a hardware problem). Likewise if the same exported pdf file is shown on Windows XP, all is well."

PDF:

http://launchpadlibrarian.net/21362015/seminar1.pdf

Comment 1 Albert Astals Cid 2009-01-27 11:29:25 UTC

Not a cairo only problem.

Comment 2 madbiologist 2010-03-06 01:06:54 UTC

Thanks Albert,

Do you have any information on where the problem lies?  Or any information on how we can determine where the problem lies?

Comment 3 Albert Astals Cid 2010-03-06 03:22:10 UTC

My guess is that the algorithm that draws the gradient "overlaps" two sections of the gradient and that results in the wrong coloring, the problem most probably lies in Gfx.cc

Comment 4 Adrian Johnson 2012-02-26 03:21:52 UTC

Created attachment 57654 [details] [review]
align fills

Here's an experimental patch for the cairo backend. It doesn't completely solve the problem but it does eliminate the seams in some cases.

Some test cases I tried it with:
https://bugs.launchpad.net/ubuntu/+source/poppler/+bug/348679/+attachment/510918/+files/test.pdf
Eliminates the seams sometimes depending on the resolution rendered at.


https://bugs.launchpad.net/ubuntu/+source/poppler/+bug/318130/+attachment/441616/+files/seminar1.pdf
Seems to eliminate the seams at all resolutions I tested.


https://bugs.launchpad.net/ubuntu/+source/poppler/+bug/387016/+attachment/606341/+files/Evince%20incorrect%20rendering.zip
Eliminates the seams for all resolutions I tested except 150ppi where the one seam is worse. This is because the the coordinates of the adjacent fill where the line is worse are not identical (0.1 difference vertically).

Comment 5 GitLab Migration User 2018-08-21 11:04:31 UTC

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