Bug 167242

Summary: thumbnails needs a lot of space compared to the pictures itself
Product: [Applications] digikam Reporter: Toralf Förster <toralf.foerster>
Component: Thumbs-ImageAssignee: Digikam Developers <digikam-bugs-null>
Status: RESOLVED FIXED    
Severity: wishlist CC: caulier.gilles, languitar, marian25
Priority: NOR    
Version: 0.9.4   
Target Milestone: ---   
Platform: unspecified   
OS: Linux   
Latest Commit: Version Fixed In: 1.0.0
Sentry Crash Report:

Description Toralf Förster 2008-07-22 19:16:07 UTC 
Version:           0.9.4-rc1 (using 3.5.9, Gentoo)
Compiler:          Target: i686-pc-linux-gnu
OS:                Linux (i686) release 2.6.25-gentoo-r7

With a resolution of 3 mega pixel each of my JPEG photos needs 1.5 MB disck space. The thumbnails are stored in PNG format resulting in ~100 KB for each large thumbnail. IMHO what's about changing the format of the thumbnails to reduce the disk space they need compared to the original image format ?
Comment 1 Mikolaj Machowski 2008-07-22 22:31:12 UTC 
This is because digiKam follows freedesktop.org .thumbnails standard.

But IMO developers should seriously consider abandoning this for several
reasons:

1. PNG thumbs are too big.
2. Not interlaced images can take long time to load.
3. Standard was written several years ago and covers only files up to
   256 pixels. With modern displays it is too small. Something up to 512
   would be good.
4. .thumbnails directory isn't very useful on other platforms.
5. .thumbnails directory isn't portable itself. If you store your
   collection with database on pluggable disk and switch computers you
   will have to recreate thumbs on new computer.
Comment 2 Johannes Wienke 2009-10-16 13:34:36 UTC 
Could this have been solved by using pfg, Gilles?
Comment 3 Johannes Wienke 2009-10-16 13:42:18 UTC 
Ehhh, should be pgf ;)
Comment 4 caulier.gilles 2009-10-16 15:00:11 UTC 
Johannes,

Yes, absolutely... PGF reduce thumbnails data size against PNG. It's wavelets compression method. PGF is around at least 1/2 of PNG, and more... this depand of image content.

Gilles
Comment 5 Marian25 2010-08-19 09:50:06 UTC 
Those thumbnails are really big compared to their parents. Sometimes the thumbnail is even bigger that the original picture. Not to mention those duplicated thumbs when you rename some folders with lots of pictures in it.

There should be some function to delete those obsolete thumbnails automatically.

That PGF stuff sounds good too.

Marian