[Bug 193967] New: VERY fast loading of thumbnails [PATCH]

[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=193967





--- Comment #18 from Gilles Caulier <caulier gilles gmail com>  2009-05-25 18:21:17 ---
#16 : I'm agree with Marcel. We must take a care to not make a bad impression
about thumbs.

#14 : agree with Mik, but speed-up improvements can be see on Single CPU
computer. On Double core, nothing (tested on 8 differents computers)

What do you think about this way :

1/ Always compute cache with SmoothScale to 256x256.
2/ In second pass,

- If size is 256, do nothing.
- If 256 > size >= 128 : use cheatscale
- If size < 128 : use FastScale (we cannot see details indeep here).

Or perhaps alwyas use cheatscale if size < 256. In all case, no need to to
touch thumb if size = 256.

Gilles

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--- Comment #19 from Mikolaj Machowski <mikmach wp pl>  2009-05-25 19:05:28 ---
BTW - very, very interesting link about generation of thumbnails:

http://www.4p8.com/eric.brasseur/gamma.html

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=193967





--- Comment #20 from Gilles Caulier <caulier gilles gmail com>  2009-05-25 19:24:19 ---
Andi,

Another way to try is to use DImg instead QImage with Fast Scale algorithm
taken from imlib2...

Gilles

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--- Comment #21 from Mikolaj Machowski <mikmach wp pl>  2009-05-25 19:48:48 ---
Gilles

1) as Andi wrote it would be good to test how generation of thumbs with
cheatScale is going
2) I think I understand misunderstanding. For you second pass is when
thumbnails were generated and only loaded from disk; for me second pass means
that when loading thumbs they are loaded in two steps - first with
FastTransformation, second time, after 2-3 seconds of inactivity in Album GUI,
with SmoothTransformation; in your terminology it would 2.5 or 3 pass.

About sizes:
size == 256 do nothing - as far as I understand this works now
size < 128 - in this area side effects of FastTransformation are really visible
so here users will be hit hard in quality

When 3 people told me that they see no difference I recompiled digiKam for each
of three variants (Smooth, Fast, cheat) to test again. Well, I see difference
between Smooth and Fast - maybe not so dramatic as I perceived yesterday - but
there is. May it be not worth to sacrifice quality? For me trade-off is worth
but for most of users of this solution it is not.

So, I propose to revert this whole thing but still investigate use of
cheatScale for .thumbnails generation.

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[Marcel Wiesweg]

https://bugs.kde.org/show_bug.cgi?id=193967





--- Comment #22 from Marcel Wiesweg <marcel wiesweg gmx de>  2009-05-26 18:43:39 ---

> So, I propose to revert this whole thing

I strongly agree. For me all thumbnails look pixellated with the current
solution.

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=193967





--- Comment #23 from Gilles Caulier <caulier gilles gmail com>  2009-05-26 19:15:55 ---
SVN commit 973246 by cgilles:

revert
CCBUGS: 193967


 M  +1 -2      thumbnailcreator.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=973246

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=193967





--- Comment #24 from Gilles Caulier <caulier gilles gmail com>  2009-05-26 19:17:00 ---
SVN commit 973247 by cgilles:

revert
CCBUGS: 193967


 M  +1 -2      digikamthumbnail.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=973247

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=193967





--- Comment #25 from Gilles Caulier <caulier gilles gmail com>  2009-05-28 12:35:27 ---
SVN commit 973970 by cgilles:

try cheat scale. It's really faster now ???
CCBUGS: 193967


 M  +8 -2      thumbnailcreator.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=973970

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=193967





--- Comment #26 from Gilles Caulier <caulier gilles gmail com>  2009-05-28 12:50:57 ---
Let's me see if thumbnails creation is a little bit faster for you now...

I still convinced that a lots of time is used to save png file to .thumbnails
cache.

Just do a simple test :

1/ start digiKam
2/ go to a console and remove ~./thumbnails (let's open digiKam session)
3/ now navigate into albums : it's really fast

Why ? Because ~./thumbnails dir disappear and digiKam cannot save in cache.
There is no more access disk.

Gilles

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=193967





--- Comment #27 from Gilles Caulier <caulier gilles gmail com>  2009-05-28 12:55:08 ---
Created an attachment (id=34073)
 --> (http://bugs.kde.org/attachment.cgi?id=34073)
Thumbnails settings panel from Gwenview for KDE3

Look like Gwenview has an option to disable thumbs cache synchronization. This
is why it can be very fast to generate thumbnails on icon view.

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--- Comment #28 from Mikolaj Machowski <mikmach wp pl>  2009-05-28 17:10:08 ---
@26, Gilles - this trick doesn't work for me, digiKam here creates .thumbnails
dir and writes there :)
@25, Gilles - yes it is faster - one thing I missed previously, in this place
digiKam creates thumbs only for non-jpg files so I see difference for TIFFs.
JPEGs are handled by local copy of jpegutils.

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--- Comment #29 from Mikolaj Machowski <mikmach wp pl>  2009-05-28 17:47:08 ---
@27, Gilles - made simple tests by commenting out code responsible for writing
of qimage to disk. There are speed gains when viewing images for first time but
when going to the same folder second time it is approximately two times slower
than with support of .thumbnails cache. For image viewer like Gwenview it is
acceptable but not for full blown image organizer like digiKam.

Could be done for Showview.

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[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=193967


Gilles Caulier <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Version|0.11.0-svn                  |1.0.0




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