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IDProjectCategoryView StatusLast Update
0008496ScribusDocumentationpublic2012-06-24 12:46
Reporterjakeg Assigned Togpittman  
PrioritynormalSeveritytextReproducibilityN/A
Status closedResolutionfixed 
Fixed in Version1.4.2.svn 
Summary0008496: Need better documentation on 'Save as PDF' re. 'Image Compression Method'
DescriptionAs per IRC discussion with Avox:

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<avox> downsampling converts them from JPG to compressed bitmap. Since
JPG compresses up to 1:20 IIRC and Zip only 1:2, it depends
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... this is not made clear at all. It's not clear that 'Automatic' compression will pick Zip rather than JPG. The dialog/tooltip currently says (when hovering the 'compression method':

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...Automatic allows Scribus to choose the best method...
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instead should be reworded to e.g.

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Automatic selects x for a and y for b
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or...

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Automatic allows Scribus to select the best method as per [link/doc]
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I have *no* idea what the Automatic method chooses or why.
TagsNo tags attached.
Patch

Activities

jghali

2009-10-07 12:58

administrator   ~0022630

Last edited: 2009-10-07 12:59

>> Automatic selects x for a and y for b

That's not as simple as that and putting that in a tooltip is not possible because the algorithm is already too complex. The compression method used depends *amongst* other things :
- on compression ratio allowed by the various compression method on a specific image
- on input image format (=> jpg is embedded as is when possible)
- on resolution settings (=> if jpg has to be resampled, it won't be embedded as is)

Generally it's not possible to determine before export begins which compression scheme will be used for a specific image

gpittman

2012-06-22 02:47

developer   ~0028256

I wonder if a manual page reference to this article on the wiki is enough - perhaps with some expansion to also show results with lossless compression to zip.

http://wiki.scribus.net/canvas/Image_DPI_and_Scaling,_and_Resultant_File_Sizes

In the end, I think one has to experiment on ones own to get a comfort level with compression and quality of output, which of course depends on the end use of the PDF.

gpittman

2012-06-24 01:43

developer   ~0028279

I've added a new article to the online manual under the Exporting to PDF section.
In addition, I added material to the wiki page to demonstrate results using Lossless method settings.
The manual article has a link to the wiki page.

Issue History

Date Modified Username Field Change
2009-10-07 10:07 jakeg New Issue
2009-10-07 12:58 jghali Note Added: 0022630
2009-10-07 12:59 jghali Note Edited: 0022630
2012-06-20 21:02 cbradney Assigned To => gpittman
2012-06-20 21:02 cbradney Status new => assigned
2012-06-22 02:47 gpittman Note Added: 0028256
2012-06-24 01:43 gpittman Note Added: 0028279
2012-06-24 01:44 gpittman Status assigned => resolved
2012-06-24 01:44 gpittman Resolution open => fixed
2012-06-24 01:44 gpittman Fixed in Version => 1.4.2.svn
2012-06-24 12:46 cbradney Status resolved => closed