[Digikam-devel] extragear/graphics/digikam/digikam

[Gilles Caulier]

2009/6/14 Gilles Caulier <caulier.gilles at gmail.com>:
> 2009/6/13 Mikolaj Machowski <mikmach at wp.pl>:
>> On Saturday 13 June 2009 17:17:37 Gilles Caulier wrote:
>>> 2009/6/13 Marcel Wiesweg <marcel.wiesweg at gmx.de>:
>>> >> Result are better than PGF, from speed and space consumption point...
>>> >
>>> > For me results with JPEG are better as well.
>>> > I have an average size of 11KB per thumbnail (db file size / number of
>>> > stored thumbnails).
>>> > Most important for me: Subjectively, loading is faster than with PGF.
>>> > (With maximum number of icons visible - no sidebars, fullscreen, minimum
>>> > thumbnail size - I can mouse wheel scroll at a reasonable fast speed
>>> > without seeing missing thumbnails)
>>>
>>> Well, what better then ? JPEG as well with a compression ratio upper
>>> than 75 (default Qt = 75) ? I recommend 85 instead...
>>>
>>> Mik, do you have tried 85 JPEG quality ? And in this case, DB will be
>>> bigger : which size compared to PGF ?
>>
>> JPEG Qt default (probably 75): 147MB for 15000 images
>> JPEG 85: 184MB
>> PGF 4: 243MB
>
>
> Thanks Mik,
>
> And now, time mesurement. Not easy to do because PC timer is not fine...
>
> in digikam/test, i just patched qtpgftest program to measure execusion
> of encoding decoding PGF and JPEG image to/from byte array with same
> DB conditions. Look result with small test.png image :
>
> [gilles at localhost tests]$ identify test.png
> test.png PNG 256x256 256x256+0+0 8-bit DirectClass 168kb
>
> [gilles at localhost tests]$ ./qtpgftest.shell
> <unknown program name>(6778)/ main: PGF Encoding time:  0.05  s
> <unknown program name>(6778)/ main: PGF Decoding time:  0.03  s
> <unknown program name>(6778)/ main: JPG Encoding time:  0.01  s
> <unknown program name>(6778)/ main: JPG Decoding time:  0.01  s
>
> If i retry test many time, with other image files, i can always see
> JPG faster... JPEG compression is 85
>
> Now, if i take a large image to test (a raw image converted to png):
>
> [gilles at localhost tests]$ identify test.png
> test.png PNG 3594x2397 3594x2397+0+0 16-bit DirectClass 24.58mb
>
> [gilles at localhost tests]$ ./qtpgftest.shell
> <unknown program name>(7467)/ main: PGF Encoding time:  3.61  s
> <unknown program name>(7467)/ main: PGF Decoding time:  2.65  s
> <unknown program name>(7467)/ main: JPG Encoding time:  0.66  s
> <unknown program name>(7467)/ main: JPG Decoding time:  0.6  s
>
> Gilles Caulier
>

Important :

libpgf is compiled in digiKam with full debug symbols : no optimizations.

JPEG codec come from QT4 with debug symbol an certainly full optimizations.

I will recompile digiKam with optimizations options to see the difference.

Gilles Caulier