[Digikam-users] jpeg compression

Mikolaj Machowski mikmach at wp.pl
Thu Jun 28 18:01:15 BST 2007

Dnia czwartek 28 czerwiec 2007, Daniel Bauer napisaƂ:
> On Donnerstag, 28. Juni 2007, Bj?rn Kvisli wrote:
> > If I understand this right, assuming that the Kodac C340 uses jpeg
> > quality of 70 internally, it makes no sense to set a higher value in
> > Digikam?
> it still makes sense, because every new save looses some more
> information. Although its not that dramatic in reality, you could think
> of percents just to better understand: then if you save the 70% with
> 100% you get 70% again, if you save it with 70% you get only 49% (70% of
> 70%) and so on.

AFAIU JPEG this is not exactly true. Quality is level of losing
information. After saving to 70 you lost all information above that and
next savings to 70 shouldn't cause losing of more detail. 

Note however that different implementations may differ and 70 level in
one program isn't exactly the same 70 in another.


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