>> "linearity" is the keyword, that is, the scanner's driver
>> cannot map the CCD to RGB data non-linearily without losing information.
Do you think slide film is linear? Definitely not.
The trick is to compress the data in a way that artifacts aren't
noticable;,i.e., so that the desired input OD range is visible on the
monitor, etc. Nikon Scan and VueScan apply different mappings depending on
settings (slide, negative, plus any curve and color corrections the user
makes. To make matters more complex, the monitor has a gamma of about 2.5,
and different computer OS's handle these differently. The standard
computer video is only 8-bits per RGB.
See <>
I have some of these mapping curves for the Nikon IV in a png format.
Mike Duncan
