Bug 30472

Summary:	tiff transparent pixels shown as black one
Product:	LibreOffice	Reporter:	Daniil Bratashov <dn2010>
Component:	Writer	Assignee:	Caolán McNamara <caolan.mcnamara>
Status:	CLOSED FIXED
Severity:	normal	CC:	caolan.mcnamara, sophi, thb
Priority:	medium
Version:	unspecified
Hardware:	Other
OS:	All
Whiteboard:
Crash report or crash signature:		Regression By:
Bug Depends on:
Bug Blocks:	126152
Attachments:	test case (odt file, it should be white, but shows ugly black drawing instead) patch to make this example work

Description Daniil Bratashov 2010-09-29 10:48:33 UTC

Transparent pixels in tiff images (both inserted from file or imported as part of some other format like docx) are shown as black one. So if we have image with some black content on transparent background we got completely black rectangle instead.

Comment 1 Caolán McNamara 2010-10-05 06:23:06 UTC

Can you attach a demo .tiff example here which reproduces this ?

Comment 2 Daniil Bratashov 2010-10-05 10:09:14 UTC

Created attachment 39184 [details]
test case (odt file, it should be white, but shows ugly black drawing instead)

Comment 3 How can I remove my account? 2010-10-06 00:58:42 UTC

Well, it isn't necessarily white that should be shown through the transparent pixels, but the page background colour, as happens for PNG images with alpha. But yeah, it seems as if the handling of TIFF with transparency is different from the handling of PNG with transparency. Maybe transparency in TIFF images isn't handled at all? So a workaround is to use PNG instead.

Comment 4 Daniil Bratashov 2010-10-06 01:12:51 UTC

(In reply to comment #3)
> Maybe transparency in TIFF images
> isn't handled at all? So a workaround is to use PNG instead.

The file where bug was found is project for article, made in MS Word with tiff images as was required by publisher, so exchanging it for png is not always a good idea. If was very confusing for original author to get the completelly black image instead, trying to open file in LO and OOo.

Comment 5 How can I remove my account? 2010-10-06 01:51:25 UTC

Sure, sure, I am not saying it isn't a bug. I just pointed out a workaround until the bug is fixed.

Comment 6 Caolán McNamara 2010-10-06 05:28:53 UTC

I'll take this one

Comment 7 Caolán McNamara 2010-10-06 05:32:25 UTC

Created attachment 39224 [details]
patch to make this example work

Comment 8 Caolán McNamara 2010-10-06 05:37:44 UTC

cmc->thb: can you have a once-over look at this impl. Does this seem reasonable to you, it definitely works for the submitted example anyway.

Comment 9 Caolán McNamara 2010-10-07 03:07:21 UTC

Committed and pushed. Might be some more scope to include some other tiff variants e.g. different depths or grayscale which also support an alpha channel.

Comment 10 sophie 2010-11-01 06:48:50 UTC

Verified in the 10_10_28_Cedric.rpm build - closing - Sophie

Comment 11 Roman Eisele 2012-05-04 02:56:01 UTC

This is a Writer issue, therefore changed the 'Component' field appropriately.