P3D Re: PHOTO-3D digest 2679

[roberts@xxxxxxxxxxxxxxxxx (John W Roberts)]

>Date: Fri, 17 Apr 1998 15:55:27 -0600
>From: Peter Davis <pd@xxxxxxxxxxxxx>
>Subject: P3D Re: PHOTO-3D digest 2679

>>Don't even bother trying to scan negatives with it. If
>>you have a negative, get a print and scan that. Several
>>orders of magnitude better.

>How about making a negative print from your positive slides, scanning that,
>and then simply reversing the colors in Photoshop or whatever?

Color negatives have a strong (orange?) color bias - this is normally
removed with filters in the printing process. If you scan and just reverse
the colors, you'll still have a color bias in the "other" direction.
If you mathematically compensate, I expect you'll lose some density range
in some of the colors in the final result (at least for a scanner that was
intended for positives). (Do professional Photo-CD scanners use filters, or 
just mathematical compensation for color bias?)

John R


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