View Issue Details

IDProjectCategoryView StatusLast Update
0016677ScribusImport / Exportpublic2021-11-09 20:55
ReporterPhoenix_IV Assigned Tojghali  
PrioritynormalSeverityminorReproducibilityhave not tried
Status closedResolutionduplicate 
Product Version1.5.7 
Summary0016677: Scribus bloats file size of single jpg image compared to output pdf
DescriptionHey, I have a single image of 1,17 mb. When I choose export as pdf with image compression set to automatic the pdf file size is 7,26 mb. When I set it to "none" it is 8,29 mb ("none" should not touch the input jpg!). Only when I set it to "Lossy - JPEG" the PDF is 1,42 mb. But with this last option I assume Scribus re-processes the image and thereby reduces quality AND increases file size slightly.

What I aimed for was to just convert an image to pdf with the right proportions / image dimensions saved alongside the PDF.

Additionally, maybe this should be a second issue, I noticed the image is very blurry in the editor, but looks fine in the output PDF.

Please find attached:
- In the zip: The original image together with a .sla project file for you to play with (created with "collect for output...")
- a screenshot of the blurry preview of a high-res image
TagsNo tags attached.
PatchNo

Relationships

duplicate of 0016150 new try harder to embed jpg images as is 

Activities

Phoenix_IV

2021-11-04 16:39

reporter  

blurry.JPG (122,456 bytes)   
blurry.JPG (122,456 bytes)   
image to pdf bloat.zip (1,229,934 bytes)

jghali

2021-11-04 19:16

administrator   ~0049333

>> When I set it to "none" it is 8,29 mb ("none" should not touch the input jpg!)

None means "No compression", so yes the input jpg will be touched as jpg data is compressed and you have instructed Scribus to uncompress the data.

jghali

2021-11-04 19:18

administrator   ~0049334

>> Additionally, maybe this should be a second issue, I noticed the image is very blurry in the editor, but looks fine in the output PDF.

This is expected : to save on memory, the editor usually loads images at a reduced resolution. The full resolution is only used on export.

jghali

2021-11-04 19:30

administrator   ~0049335

>> When I choose export as pdf with image compression set to automatic the pdf file size is 7,26 mb.

Your image uses a progressive jpeg encoding which is not safe to use in PDF. When this is the case, the Automatic mode has to re-encode the image and prefers to uses lossless compression in order to avoid loss of quality.

Phoenix_IV

2021-11-05 09:37

reporter   ~0049337

Thank you for the reasonable explanation. I am trying to find a source on the bit "progressive jpeg encoding which is not safe to use in PDF". Can you reference me some specification?

On the side track: I am surprised the resolution is not a little higher in the editor - to a point where images are not obviously blurry.

jghali

2021-11-06 11:34

administrator   ~0049341

This is a case of specifications vs reality. While the PDF specifications allows the progressive jpeg encoding, a number of RIPs do not support that encoding. The cases where a jpeg file cannot be embedded as is in PDFs for safety reasons are in fact not limited to that one. I give a more extended list in issue 0016150, for eg:
- JPEG file use progressive encoding
- JPEG exif data uses non default rotation (eg: images using portrait orientation taken with digital cameras)
- JPEG file uses CMYK colorspace: would force to use a PDF feature which is regularly misinterpreted by RIPs

Phoenix_IV

2021-11-08 22:47

reporter   ~0049342

I see. So it is about maximizing compatibility for those who do not consider all factors in PDFs. I consider this ticket as a duplicate of https://bugs.scribus.net/view.php?id=16150

jghali

2021-11-09 20:55

administrator   ~0049343

Yes, it is. Hence closing this issue as a duplicate.

Issue History

Date Modified Username Field Change
2021-11-04 16:39 Phoenix_IV New Issue
2021-11-04 16:39 Phoenix_IV File Added: blurry.JPG
2021-11-04 16:39 Phoenix_IV File Added: image to pdf bloat.zip
2021-11-04 19:16 jghali Note Added: 0049333
2021-11-04 19:18 jghali Note Added: 0049334
2021-11-04 19:30 jghali Note Added: 0049335
2021-11-05 09:37 Phoenix_IV Note Added: 0049337
2021-11-06 11:34 jghali Note Added: 0049341
2021-11-08 22:47 Phoenix_IV Note Added: 0049342
2021-11-09 20:55 jghali Assigned To => jghali
2021-11-09 20:55 jghali Status new => resolved
2021-11-09 20:55 jghali Resolution open => duplicate
2021-11-09 20:55 jghali Note Added: 0049343
2021-11-09 20:55 jghali Relationship added duplicate of 0016150
2021-11-09 20:55 jghali Status resolved => closed