On 5/19/2016 12:35 PM, Chuck Norcutt wrote:
What you're calling FastStone's assessment of the image quality is actually a measure of the JPEG compression level.
There doesn't really appear to be any standard by which JPEG compression is measured. Some, like FastStone, appear to
be using a percentage from 1-100 but exactly what that means I don't think is defined. Photoshop uses a range of
quality levels specified as integers between 1 and 12 but it then groups those values into quality ranges.
Yup
So, whatever value FastStone is using has nothing to do with what you or the camera or the lens produced.
Yup
It has everything to do with the degree of image compression used when the image was created or saved as a JPEG after
editing.
But it's tricky. It's so easy to assume the original compression has been reversed with no loss, and thus select the
same % again. But if the original was 80%, and after re-opening I save it again at 80%, I end up with something in the
vicinity of what 64% compression of the original would have been. More likely worse.
Help, I'm Shrinking Moose
--
What if the Hokey Pokey *IS* what it's all about?
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