Issue 37400 - PDF Export plain: use different compression for images and line drawings
Summary: PDF Export plain: use different compression for images and line drawings
Status: CLOSED FIXED
Alias: None
Product: gsl
Classification: Code
Component: code (show other issues)
Version: 680m58
Hardware: All All
: P3 Trivial (vote)
Target Milestone: 3.4.0
Assignee: h.ilter
QA Contact: issues@gsl
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2004-11-18 14:07 UTC by rmaris
Modified: 2017-05-20 10:31 UTC (History)
2 users (show)

See Also:
Issue Type: ENHANCEMENT
Latest Confirmation in: ---
Developer Difficulty: ---

Attachments
test document cotaining 1bit images (12.14 KB, application/vnd.oasis.opendocument.text)
2011-01-20 16:45 UTC, philipp.lohmann 		no flags Details
Add an attachment (proposed patch, testcase, etc.)

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Description rmaris 2004-11-18 14:07:04 UTC 
Usually, screenshots are stored as png or other compact, no-loss formats. Most 
screenshots are better compressed using png over jpeg. Since screenshots of 
graphs and GUI's mostly contain lines etc., jpeg artefacts are clearly viewable 
(almost regardless quality stage).

The problem with the jpeg exports is that all the graphs in the document are 
converted to jpeg format, regardless the internal storage format, which is 
mostly determined upon graph insert time (e.g. jpg resp. png/tiff.

A differentiated handling would result in better and smaller pdfs. An experiment 
with adobe distiller has proved this on a sample document.
Comment 1 christof.pintaske 2004-11-18 14:30:16 UTC 
duplicate, already fixed in OpenOffice 2.0

*** This issue has been marked as a duplicate of 20142 ***
Comment 2 christof.pintaske 2004-11-18 14:32:32 UTC 
nope, not duplicate, reopen
Comment 3 christof.pintaske 2004-11-18 14:35:28 UTC 
changed title. No chance for 2.0
Comment 4 christof.pintaske 2005-02-22 17:01:50 UTC 
cp->pl: rfe for pdf
Comment 5 philipp.lohmann 2005-02-22 17:25:31 UTC 
PDF only supports JPEG compression for multicolor bitmaps, for monochrome
bitmaps it supports CCITTFax and JBIG2. Aside from that Flate decoding is
supported but of course is not as effective since it is lossless; JPEG and Flate
are selectable by the user already in 2.0; for jpeg the user can also determine
the compression level for the exported bitmaps.

So in short we could only add one of the monochrome compression methods to
improve the situation for 1 bit images.
Comment 6 philipp.lohmann 2011-01-12 16:18:03 UTC 
implemented writing 1bit images with CCITT G4 fax encoding (which is supposed to
be on average a little better than Inflate) for black&white bitmaps.

committed in CWS vcl118
Comment 7 philipp.lohmann 2011-01-20 16:45:14 UTC 
Created attachment 75596 [details]
test document cotaining 1bit images
Comment 8 philipp.lohmann 2011-01-20 16:47:21 UTC 
please verify in CWS vcl118, testdocument with corresponding 1bit images attached.
Comment 9 h.ilter 2011-01-27 10:27:54 UTC 
Verified with cws vcl118 = OK; It creates a smaller pdf file using the bugdoc.