[LargeFormat] Scanning B&W negs in colour

[Clive Warren]

At 4:06 pm -0600 21/2/01, Pam Niedermayer wrote:
>
>
>Clive Warren wrote:
snip
>  >
>>  "The current PostScript specification only allows for 254 halftone steps
>>  (the way a shade of grey is represented in print, 254 steps with pure white
>>  and pure black which makes 256 total). The extra grey shades (bit depth)
>>  may help to improve the scanners optical density (OD) range if implemented
>>  properly. This can give you better shadow detail. Unfortunately most
>>  moderately priced 30- and 36-bit desktop scanners implement the the
>>  expanded bit depth only in color, opting for a more common lookup table
>>  (LUT) approach to greyscale scanning."  Taken from |The Scanning FAQ
>>  Compiled and maintained by Jeff Bone  -
>>  http://www.infomedia.net/scan/The-Scan-FAQ.html
>>
>>  This would explain why it is better to scan in colour and manipulate
>  > post-scan using image editing software.
>

>This is a little confusing. Postscript is a printing/display (ATM,
>e.g., is a subset of Display Postscript) technology, not a scanning
>technology. The context of Postscript in this explanation is that
>since PS printers only print to 256 levels, the scanner makers don't
>bother to scan more grayscale levels, since their assumption is that
>you'll be scanning digital prints.
>
>I'm not sure whether it's true or not that the scanner makers have
>stopped at 256; but the article you're paraphrasing/quoting is at
>least 4 years old.
>
>Also, the scanning software used is a major driver in the process; so
>you may want to investigate getting Ed Hamrick's VueScan, which comes
>highly recommended by the multitudes (I haven't tried it because I've
>got this Opal Ultra with Linocolor stuff), think there's a free demo
>version available. His site is at:
>
>http://www.hamrick.com/vsm.html
>
>Pam


Thanks for the VueScan suggestion - as soon as I saw the name it 
reminded me of some posts elsewhere about the software and how good 
it is. The SilverFast software would take a lot of beating  - it 
scans in colour by default for B&W negs. If the scanner manufacturers 
supply software which does indeed limit the greyscales used to scan 
B&W negs then the set up using the ScanMaler4 and SilverFast is not 
restricted in greyscale levels.

I was a little disappointed with the 4x5 B&W neg. scans carried out 
so far, but I have only tried a couple so it may be the case that 
more experimentation is needed. When the limits of the SilverFast 
software is reached then VueScan may be worth a look if the B&W negs 
are still unsatisfactory.

My assumption about the Postscript explanation was that the scanner 
manufacturers were attempting to help users by limiting the file size 
given the technology limitations (4 years ago?) of Postscript 
printers for printing out rather than any factor related to the image 
being scanned.  The scanned image could be a neg (more unlikely 4 
years ago on a flat bed) or a photograph/print etc.

Thanks for pointing out the age of the article.

Do you get good results scanning 4x5 negs on the Opal Ultra?

-- 
All the best,

             Clive Warren   http://www.f32.net
                            Large Format travel and stock photography