[Bug 233094] New: Thumbnails blurry (when scaling) on PowerPC platform (big-endian)

[Vlado Plaga]

https://bugs.kde.org/show_bug.cgi?id=233094

           Summary: Thumbnails blurry (when scaling) on PowerPC platform
                    (big-endian)
           Product: digikam
           Version: 1.2.0
          Platform: Debian testing
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: NOR
         Component: general
        AssignedTo: [hidden email]
        ReportedBy: [hidden email]


Version:           1.2.0 (using KDE 4.3.4)
Compiler:          GCC 4.4.3
OS:                Linux
Installed from:    Debian testing/unstable Packages

This problem was already partly discussed in #224999 "Thumbnails blury after
upgrade to 1.0.0 from 0.10" (starting with comment no 24), and I suspect it
might be related to #210580 "digiKam crashes on PPC Linux when changing
thumbnail size".

The problem with digiKam 1.2.0 on my PowerPC Debian system is that thumbnails
appear extremely blurry as soon is I scale them down a little.

As described in my comments to #224999 thumbnails are always blurry when
generated in Ubuntu 10.04 on the same PowerPC computer.

I get clear, scalable thumbnails, when I compile digiKam with
"-DENABLE_THUMBS_DB=no" - but (re)-loading of thumbnails, also when I change
their size or just change a picture's rating, is a lot faster with the new
Thumbs DB method. So having this thumbnail sharpness problem fixed properly
would probably make digiKam usage a lot more convenient for me (and maybe some
others too)!

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Marcel Wiesweg]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #1 from Marcel Wiesweg <marcel wiesweg gmx de>  2010-04-02 22:50:25 ---
One thing to rule out is a problem with libpgf. For this test, change in
libs/threadimageio/thumbnailcreator.cpp, line 498,
    dbInfo.type             = DatabaseThumbnail::PGF;
to
    dbInfo.type             = DatabaseThumbnail::PNG;

From now on you will create PNG thumbnails in your database. Please check if
that makes any difference.

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=233094


Gilles Caulier <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |[hidden email]




--- Comment #2 from Gilles Caulier <caulier gilles gmail com>  2010-04-03 12:11:14 ---
If there is a difference, this problem will be relevant of libpgf running under
PPC computer. Please confirm... In this case, i will contact libpgf team for
feedback

Gilles Caulier

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Vlado Plaga]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #3 from Vlado Plaga <rechner vlado-do de>  2010-04-03 19:11:36 ---
Yeah, success! It is libpgf again. Thanks for the quick reaction, Marcel and
Gilles! Now I've also got the best digiKam ever, finally. :-)

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=233094


Gilles Caulier <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|general                     |Thumbnails
            Summary|Thumbnails blurry (when     |libpgf relevant :
                   |scaling) on PowerPC         |thumbnails blurry (when
                   |platform (big-endian)       |scaling) on PowerPC
                   |                            |platform (big-endian)




--- Comment #4 from Gilles Caulier <caulier gilles gmail com>  2010-04-03 19:56:14 ---
Ok thanks. I CC libpgf team for info.

Gilles Caulier

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=233094


Gilles Caulier <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |rschweizer@schweizer-inform
                   |                            |atik.ch




--- Comment #5 from Gilles Caulier <caulier gilles gmail com>  2010-04-03 20:42:27 ---
Raphael,

Please look at this file. Sound like another libpgf problem under PPC computer.
Here, Vlado see thumbnails blured in digiKam icon view. It's typically a
compression problem with libpgf, i think.

Code relevant in digiKam is there :

http://lxr.kde.org/source/extragear/graphics/digikam/libs/threadimageio/pgfutils.cpp#83

This method is used to create a bytearray of a compressed PGF image
computed from a QImage instance. This bytearray is stored in digiKam Database
as well.

To extract PGF bytearray from database and create a QImage, we use this method
:

http://lxr.kde.org/source/extragear/graphics/digikam/libs/threadimageio/pgfutils.cpp#53

The rest of thumbnail process in digiKam is Qt4 based code, and the problem is
not there.

About libpgf compiled in digiKam core, we use this CMake code :

http://lxr.kde.org/source/extragear/graphics/digikam/CMakeLists.txt#1002

There is no special compilation flag set for libpgf.

Finally, lipgf code is there :

http://lxr.kde.org/source/extragear/graphics/digikam/libs/3rdparty/libpgf/

Thanks in advance for your help

Gilles Caulier

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Raphael Schweizer]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #6 from Raphael Schweizer <rschweizer schweizer-informatik ch>  2010-04-04 10:14:46 ---
Thank you for reporting and all the helpful details.
A PPC will be at my disposal starting April 6th. I'll look into it immediately.

Raphael Schweizer

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #7 from Gilles Caulier <caulier gilles gmail com>  2010-04-04 10:28:05 ---
Raphael,

Great. If you need more info, ask to Vlado. he has a PPC computer (I don't have
it).

If you want to compile digiKam, just post your questions here. All developers
are in this room.

Gilles Caulier

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Raphael Schweizer]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #8 from Raphael Schweizer <rschweizer schweizer-informatik ch>  2010-04-07 18:12:51 ---
Gilles,

Investigation has started.
Using Ubuntu 9.10 and the current pgf codec w/ console I could not find a
difference between big and little endian encoded images so far. I'm currently
trying to compile my own svn version of digiKam (repository version is at
1.0.0, which crashes on PPCs, as we know :-D) CMake says:
--
CMake Error at libkipi/CMakeLists.txt:60 (INSTALL):
 install FILES given no DESTINATION!
CMake Error at libkipi/pics/CMakeLists.txt:1 (KDE4_INSTALL_ICONS):
 Unknown CMake command "KDE4_INSTALL_ICONS".
--
What am I doing wrong?

I suppose digiKam calculates the thumnail images once and scales these images
afterwards? So if the thumbnails look OK after generation and get blurry after
scaling, where does libpgf come in? I do, however, not understand why the
problem disappears if dbInfo.type = DatabaseThumbnail::PNG

Raphael Schweizer

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #9 from Gilles Caulier <caulier gilles gmail com>  2010-04-07 18:25:25 ---
To compile digiKam, you need to compile and install shared libraries from
kdegraphics, and after compile digiKam and kipi-plugins. Look instruction here
:

http://www.digikam.org/drupal/download/KDE4

Using svn trunk version is the best, because it's current code.

To solve external dependencies, look in README files, all is explained indeep.
It's not difficult...

About PNG stuff, yes, this is strange. PNG encoder is libpng based (through Qt4
API), and PGF codec is dropped to render thumbs. This is why i suspect libpgf
here.

Gilles Caulier

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Vlado Plaga]

https://bugs.kde.org/show_bug.cgi?id=233094


Vlado Plaga <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |[hidden email]




--- Comment #10 from Vlado Plaga <rechner vlado-do de>  2010-04-07 19:02:27 ---
My suggestion for compiling digiKam in Ubuntu 9.10:

Get the digiKam 1.2.0 tarball and follow instructions on that website:
http://www.digikam.org/drupal/download?q=download/tarball

You can get all build dependencies for digiKam by doing
# apt-get build-dep digikam

It is also possible to create proper deb packages, but compiling that way takes
longer, because it creates both a normal and a debug version:
http://mail.kde.org/pipermail/digikam-users/2010-March/010083.html

I don't think it is necessary to experiment with the latest code, if the
problem is already there in version 1.2.0.

Raphael, I hope you can reproduce and solve my problem (although it is not
urgent for me, thanks to the PNG workaround)! I experienced different results
on Debian and on Ubuntu 10.04 - digiKam on Ubuntu 9.10 might behave differently
again.

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #11 from Gilles Caulier <caulier gilles gmail com>  2010-04-07 19:14:42 ---
Vlado,

I has a question for you ? Can you test again using PGF codec on your computer,
and change compression level of PGF image. There is only an hardcoded value to
change in source code here :

http://lxr.kde.org/source/extragear/graphics/digikam/libs/threadimageio/thumbnailcreator.cpp#504

The last parameter '4' is PGF compression level. Using smaller value compress
lesser. '0' value is lossless compression as PNG.

Can you test with 3, 2, 1, and 0 to see if blurring effect disappear ?

Note : Of course don't forget to revert changes done following #1 from Marcel
to use PGF codec.

Thanks in advance

Gilles

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Vlado Plaga]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #12 from Vlado Plaga <rechner vlado-do de>  2010-04-08 14:33:09 ---
Created an attachment (id=42593)
 --> (http://bugs.kde.org/attachment.cgi?id=42593)
comparison between PGF compression levels 4 and 3

Gilles, you seem to be on the right track. Changing PGF compression levels has
a significant effect, as can be seen in the attached comparison between levels
4 (default) and 3. I did these tests with digiKam 1.2 on Debian sid / PPC. I
also checked level 0 (before level 3), but I can't see a significant difference
between 0 and 3, so I did not bother attaching a level 0 screen-shot.

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #13 from Gilles Caulier <caulier gilles gmail com>  2010-04-08 14:48:02 ---
Vlado,

Thanks to comparing compression levels. i will set PGF compression to 3
immediately in source code.

Raphael,

Any comments about difference between PGF compression level 3 and 4 ? Why the
image become blurred ? It's a side effect of wavelets compression ? If yes, why
i cannot reproduce i never see that with JPEG 2000 ?

Gilles Caulier

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Raphael Schweizer]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #14 from Raphael Schweizer <rschweizer schweizer-informatik ch>  2010-04-08 16:22:19 ---
Gilles,

starting with compression level 4 downsampling is used (see DownsampleThreshold
in
http://lxr.kde.org/source/extragear/graphics/digikam/libs/3rdparty/libpgf/PGFtypes.h#53),
which may explain a small difference. Judging from Vlado's screenshots there
must be something else. Perhaps libpgf is reporting wrong level sizes on PPCs,
such that scaling
(http://lxr.kde.org/source/extragear/graphics/digikam/libs/threadimageio/pgfutils.cpp#129)
does not work correctly. I'll check that.

Raphael Schweizer

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Raphael Schweizer]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #15 from Raphael Schweizer <rschweizer schweizer-informatik ch>  2010-04-14 18:47:14 ---
Created an attachment (id=42783)
 --> (http://bugs.kde.org/attachment.cgi?id=42783)
PGF thumbail channel map patch

Gilles,

the blurriness issue is finally demystified:

1) on big endian systems, libpgf did a wrong YUV transform of thumbnails
(missing ARGB / BGRA map) which led to increased data size
2) libPGF crashed when a ARGB PGF was loaded (short channel map).

a) loadPGFScaled only works with (A)RGB PGFs (some mapping PGF.Mode <->
QImage.Mode is needed)
b) Judging from screenshots thumbnail images are stored 256x256 but displayed
254x254 (with black border). Resizing introduces blurriness.

Issues 1) & 2) are solved with the attached patch. a) and b) are outside the
scope of this bug.

Please note that a rebuild of the thumbnails is needed on big endian systems.

Raphael Schweizer

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #16 from Gilles Caulier <caulier gilles gmail com>  2010-04-14 21:27:47 ---
Thanks Raphael,

I will patch digiKam.

Yes thumbs are 256x256 and are downscaled to 254x254. I thinl that image must
be cropped instead. Marcel ?

Gilles

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #17 from Gilles Caulier <caulier gilles gmail com>  2010-04-14 21:33:04 ---
SVN commit 1114868 by cgilles:

patch from Raphael Schweizer to play properly with PGF image under PowerPC
computer
CCBUGS: 233094


 M  +17 -4     pgfutils.cpp  


WebSVN link: http://websvn.kde.org/?view=rev&revision=1114868

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Marcel Wiesweg]

https://bugs.kde.org/show_bug.cgi?id=233094





--- Comment #18 from Marcel Wiesweg <marcel wiesweg gmx de>  2010-04-14 22:20:44 ---
Referring to this code?
void ThumbnailLoadThread::slotThumbnailLoaded(const LoadingDescription&
description, const QImage& thumb)

        pix = QPixmap(w + 2, h + 2);
        QPainter p(&pix);
        p.setPen(QPen(Qt::black, 1));
        p.drawRect(0, 0, w + 1, h + 1);
        p.drawImage(1, 1, thumb);

The pixmap is created two pixels larger than the loaded thumbnail. No scaling
is done here.

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel

[Gilles Caulier-4]

https://bugs.kde.org/show_bug.cgi?id=233094


Gilles Caulier <[hidden email]> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED




--- Comment #19 from Gilles Caulier <caulier gilles gmail com>  2010-04-14 22:23:49 ---
Thanks Marcel,

So nothing can be done anymore in this file. I close it now.

Gilles Caulier

--
Configure bugmail: https://bugs.kde.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.
_______________________________________________
Digikam-devel mailing list
[hidden email]
https://mail.kde.org/mailman/listinfo/digikam-devel