On 6/14/2012 4:34 PM, Chuck Norcutt wrote:
> I agree with Ken. As soon as I saw "dark scan" I knew something is
> wrong with the scanning. If anything the scan should be normal or light
> if the histogram doesn't bump up against both ends.
You are working from an assumption that may not be true, that the initial SF
output is gamma adjusted. Tina refers to a
SF raw output file and difficulties in getting it right in LR, PS, etc.
Raw output from VueScan and 16 bit output from DCRaw are both linear and look,
if one doesn't know what's going on,
terribly dark. Look for "LINEAR HISTOGRAM" about a quarter of the way down this
page to read a succinct description with
illustrations. <http://www.guillermoluijk.com/tutorial/dcraw/index_en.htm>
Although I don't know for sure, we would need to know more before assuming that
the slide and/or the scan was
underexposed. The fact that SF's follow on processing makes everything right
may suggest that a linear output
intermediate file was what Tina was trying to work with.
It's relatively easy to apply gamma in PS, but not with the usual adjustment
tools. Details are further down in the
above link.
I had to do this all the time when working with RAW files created by the CHDK
add-on firmware for the A710 and A650.
DCRaw (and RawTherapee?) was the only Raw converter that would recognize and
convert those files, and 16 bit output
meant linear data.
Non Linear Moose
--
What if the Hokey Pokey *IS* what it's all about?
--
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/
|