Digital BW, The Print

--- In DigitalBlackandWhiteThePrint@y..., Todd Flashner <tflash@e...> 
wrote:
(snip)

> 
> Martin had sent me two raw files from the same image scanned on two
> different scanners. I don't remember if both scanners have the same 
bit
> depth though; lets assume they do. Before manipulations one's 
histogram
> seemed much narrower than the other, so I naturally assumed the 
scan with
> the wider histogram was the preferable scan. However, I casually 
expanded
> each one to look decent, not even trying to make them look exactly 
alike,
> and when I checked their histos after the adjustments I was 
surprised at how
> alike they looked. Should I now assume that one scanner probably 
just low
> bit justified the data, while the other high bit justified it's 
data?
>

Todd, Austin,

The two scanners had the same bit depth, 14-bit. One was a Linoscan 
1400 flatbed running under Vuescan that gave a 16-bit file with an 
extremely compressed histogram. The second was a Polaroid SprintScan 
120 running under Polacolor Insight which gave a 16-bit file whose 
histogram was about 3 times wider for the same image.

My question is that how do we know we are getting a raw scan? We have 
to interface to the scanner with a piece of software on the computer 
and the firmware in the scanner itself. I know vuescan states that if 
it cannot access the 12 or 14 bit mode of the scanner it takes 8-bit 
data and places it in a 16-bit space but does not indicate whether it 
is doing this or not. I seem to recall that some 12 and 14-bit 
scanners scan at the bit depth but only output 8-bit.

Is there anyway to tell what bit depth was actually written to the 16-
bit "raw" scan file?

Martin


(snip)