[mythtv] [mythtv-commits] mythtv commit: r18037 by stuartm

Stuart Morgan stuart at tase.co.uk
Sun Aug 3 21:14:01 UTC 2008

On Sunday 03 August 2008 22:01:22 Stuart Morgan wrote:
> On Sunday 03 August 2008 21:26:37 mythtv at cvs.mythtv.org wrote:
> > Seems 90 wasn't high enough for the QT jpeg encoder, I was using Gimp and
> > other applications as a guideline where 90 would give crystal sharp
> > images at around 50Kb for a standard photo. QT produces 29Kb images and
> > lots of artifacts at that same level. Pulling a figure out of the air and
> > trying 96 instead.
> Ok, it looks like the JPEG quality is not to blame, something else is going
> on here and I can't see what it is. Even switching to png the quality is
> rubbish.
> Compare the image below - left is scaled/encoded by Gimp and the right is
> the thumbGenerator in QT:
> http://miffteevee.co.uk/imagebin/gimp_vs_qt.png
> Now we know QT is capable of better, it scales the theme images just fine
> so it's something to do with the thumbgenerator. Can anyone spot the bug?

Nevermind, it was caused by using embedded previews in the EXIF data that were 
smaller than the target thumbnail so we were scaling up which never looks 
great. Additionally saving a jpeg for a second time introduces additional 
artifiacts to the image.

Should now be fixed in trunk.

Stuart Morgan

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