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Re: [OM] IMG: Faviana and Reymundo

Subject: Re: [OM] IMG: Faviana and Reymundo
From: Moose <olymoose@xxxxxxxxx>
Date: Thu, 14 Jun 2012 21:29:34 -0700
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?
-- 
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