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

[Gilles Caulier]

2009/6/14 Gilles Caulier <caulier.gilles at gmail.com>:
> 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
>>

Look time measurements with release mode (same image) :

[gilles at localhost tests]$ ./qtpgftest.shell
PGF Encoding time:  1.91  s
PGF Decoding time:  1.29  s
JPG Encoding time:  0.66  s
JPG Decoding time:  0.6  s

PGF is better but JPEG is always better...

Gilles