Re: Sprintscan 120 issues/findings (comments welcomed)

[East75th <east75th@xxxxxxxxxxxxxxxx>]

The elevated clipping point of 30 in NikonScan 3 appears when scanning 
negatives. In addition to the mis-set low end, the bug appears to involve 
an inadvertent application of a gamma function to the image.  You can 
partly undo the bug in PS by using the levels function.  You can confirm 
this by scanning a negative as a positive, inverting, and comparing its 
histogram to the one for the negative scan.  After the loss of information, 
setting of the BW point, application of the gamma correction, the histogram 
looks a lot messier than scanning positive and inverting.

Interestingly, Rafe has pointed out that the screen gamma setting affects 
where NS sets the clipping point.
If you scan as a positive this bug doesn't occur.

>I've read that some printers use only black ink below about this value, 
>and color above.
>
>Could this be something that Nikon has set deliberately, anticipating 
>printing without black or is that stretching an observation too far?

This would be an arrogant presumption on their part, most of my scans never 
go to an ink jet printer.  It also defeats the purpose of the scanner's 
higher D-max.  I want to keep as much information as possible in the stored 
image.  Plainly it's a stupid and easily correctable bug.

Dane Kosaka





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