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

Mikolaj Machowski mikmach at wp.pl
Sun Jun 14 21:20:36 CEST 2009


On Sunday 14 June 2009 14:35:42 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.
>
> For me, as Mik said, JPEG give artifact on thumbs, with 256x256 size,
> especially with image which have geometric forms (wall, houses,
> momuments) or high subject contrast as flowers taken in macro mode and
> with large zone with same colors ( it's not visible with complex
> images composition with high levels of details) . Sound like
> anti-aliasing is not visible.
>
> I tried 90 compression instead 85, but it still visible.

Gilles, for artifacts and quality of image in rescaling more important than 5 
points is chroma sampling. Bare Qt uses 2x1x1 or worse. To improve quality of 
JPEGs digiKam should use its own processes which can use highest possible 
sampling of 1x1x1.

Just for information - my collection of 15000:
226M    thumbnails-digikam.db     <- JPEG q=90
184M    thumbnails-digikam-jpeg.db <- JPEG q=85
243M    thumbnails-digikam-pgf.db <- PGF

About database: did you consider mysqld? Due to Amarok it should be available 
without problems on most Linux desktop systems.

m.


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