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From "Jim Michaels" <>
Subject [allura:tickets] #4897 Don't unnecessarily re-encode screenshots for PSP [ss479]
Date Wed, 14 Aug 2013 11:12:48 GMT
jpegs: the artifacts can be eliminated by raising the quality value. this is well known about
jpegs. this also increases the file size, which is another well known aspect.
different vendors use different ways of expressing the quality. some have the range ends swapped,
and the range endpoint values have different values from one vendor to another. so this seems
to be implementation-specific.

I don't know about jpeg quality Allura provides, such as if it is hard-coded, or whether that
is customizable somewhere.

I am having issues with the thumbnails. from my experience, png's are usually fairly larger
than jpegs, and are only good when you wish to reproduce detail like pixels faithfully (such
as screenshots). an few existing jpeg images from a camera saved-as PNG with PS or GIMP will
confirm this. you can use ttcalc or a calculator to do this: PNGsize/JPEGsize which if you
multiply this ratio by your existing JPEG database size, will give you the new storage size
in PNG.


** [tickets:#4897] Don't unnecessarily re-encode screenshots for PSP [ss479]**

**Status:** open
**Labels:** support p3 
**Created:** Tue Sep 11, 2012 02:56 PM UTC by Chris Tsai
**Last Updated:** Tue Aug 13, 2013 02:47 PM UTC
**Owner:** nobody


>Currently screenshots are converted into JPG regardless of uploaded image format. Encoding
JPG settings are rather low (~60-75 quality of original image) and give a lot of visual artifacts,
especially in case of gradients. PNG images often have file size comparable or even less than
of resulting JPG (in my case ~20-30%).

>Suggestion: Do not encode screenshots uploaded if encoded JPG is lager then original.

>Thank you.

When I save the files from the PSP, they come up as PNGs for me, but they are indeed larger
than the original uploaded files.

See attachments on [forge:site-support:#479] for examples of the re-encode artifacts.


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