Hi Chuck and Moose,
I've been following this at a distance, because I decided a long time
ago to make all saves as TIFF files, unless the purpose of the image
requires a JPEG. If so, I save the final TIFF as a JPEG. Sometime in
the past few months, I had a requirement that set a size limit on the
JPEG submitted, so I had to reduce the quality slightly to meet the
limit, but I can't recall what that situation was.
Jim Nichols
Tullahoma, TN USA
On 5/19/2016 4:41 PM, Moose wrote:
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
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