Re: [Gimp-user] Why does saves as JPG default to quality 85?

[Patrick Shanahan <ptilopteri gmail com>]

* Ofnuts <ofnuts laposte net> [01-01-70 12:34]:
> On 03/23/2012 09:20 PM, Liam R E Quin wrote:
> > every time you load and
> > save a JPEG file the quality is reduced and information is lost.
> Not true... if nothing changes the algorithm is stable (decoded values get
> re-encoded to the same values). You lose quality if you recompute something
> different; changed settings, changed pixel values, changed 8x8 boundaries
> (image crop).

Well, it is true and very easily proven.

Open a jpg file and save it.  Then open the just saved file and save it
again at the save compression level.  Then do a diff or simply check the
file sizes.

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