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Re: filmscanners: VueScan Histogram




----- Original Message -----
From: "Colin Maddock" <cmaddock@clear.net.nz>
To: <filmscanners@halftone.co.uk>
Sent: Sunday, December 16, 2001 7:32 PM
Subject: Re: filmscanners: VueScan Histogram


> David Gordon asked:  How do you know where to clip the black and white
points?
>
> I always leave black clipping at 0, and white clipping at a minimal
amount, perhaps 0.1, so that the VueScan scan contains all the tonal range
that was on the neg/slide.

*From my observations if you just scan with the WP at 0.1 as default, you
can compress the tonal values rather than making sure the image ocupies the
full range available. If your image allows a WP of say 0.4 just before
clipping then the available range isn't wasted in the 0-0.4 area*

Any further clipping of the end points for cosmetic reasons etc can be done
as part of the operations in the image editing program, using, say, the Info
facility to search the levels.

*Making sure the actual points at just before clipping are fully filling the
histogram maximises the image quality output to file etc. I also found
before the histograms were implimented that the best visual tonal range on
screen ie unclipped whites but not vailed or flat as is often the case with
WP <0.3 actually do fill the histogram perfectly. The image editor then can
do the 'cosmetics' if required on an image mapped to make use of the full
available dynamic range.*

Philip Elkin







 




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