Digital BW, The Print

On 03/01/2008 AnnMarie Tornabene wrote:
> Well, this is what I gathered from running the test. I scanned in at
> 4800 dpi, then scanned the same negative at 12,800 dpi and as I
> suspected, got a better result from the latter. There is a huge
> amount of pixelation, especially in the skin tone, and some quick
> jumps between tones when I scanned in at 4800. Then I tried scanning
> at 3200 because sometimes there is a key resolution to use that works
> and anything above it gives similar results. Well, it did look
> slightly better than the 4800 dpi scan, but still not as nice as the
> 12,800.

With any CCD scanner, you'll generally get much better results if you scan 
at the optical resolution and do any upsizing in Photoshop rather than the 
scanner software. PS has better interpolation algorithms, where I am not 
aware of any OE scanner software that does anything better than crude 
nearest neighbour interpolation.

Epson invariably cheat on optical resolution somewhat, by using 0.5px 
stepping to give a more impressive number. 0.5 stepping does give slightly 
better results than 1px, but not 2x as good. The 4990 claims 4800 x 
9600dpi optical resolution at 
http://www.epson.co.uk/scanners/Epson-Perfection-4490-Photo-Scanner.htm
and that number is assymettric because of the half-pixel stepping.

It's unlikely the driver allows 4800x9600; I'd expect either 4800x4800 or 
9600x9600 - the first is the true optical resolution with 1px stepping, 
the latter involves 0.5 stepping and interpolation on the x-axis. Whatever 
small advantage is conferred by 0.5 px stepping will be lost by crappy 
horizontal interpolation. It's marketing nonsense, basically.

I'd expect 4800x4800 and any upsizing done in PS to give the smoothest 
results. But the real downside in most flatbeds is mediocre optics that 
limits resolution to way below what the pixel count is capable of. There 
are exceptions but they are usually very expensive. Some upmarket 
Microteks do well, or for the truly wealthy and fastidious, track down a 
Scitex Everssmart - that can scan 40 35mm all at once, and they cost 
around $25k before they went out of production, and they are about the 
size of a small fridge.

All the cheap filmscanners are quite poor as well, OK for consumer snaps 
but not decent A4's or larger. You just can't have a quality lens system 
with precision engineering on the cheap. It needs to be as good as the 
camera and lens system, if anything slightly better.

35mm needs 4000ppi minimum to minimise issues with grain aliasing, and 
optics to match. 4000ppi+ models from Nikon, Polaroid /Microtek, Minolta 
are all good, with a different balance of good and not so good points. The 
same names are responsible for the better MF scanners too, at much higher 
cost. Imacon are very good but costly.

Sadly Polaroid and Minolta are now defunct, so the choice is pretty 
limited unless you buy s/h. The Minolta Dimage 5400 35mm scanner 
consistently sells s/h on eBay for as much or more than it cost new, 
despite the fact that Minolta seemed to have persistent QC issues with 
every scanner they ever made. The Microteks still exist but seem to be 
hard to find, and are fundamentally the same as the defunct Polaroids 
(Polaroid specified and commissioned the design and build from Microtek). 
Which leaves Nikon as the sole survivor. I'm not a fan of their LED 
lightsources for a number of reasons (Callier effect enhances defects and 
grain aliasing, low intensity needs large aperture lens leading to focus 
problems with bowed film). But they are good nonetheless.

For anyone who really wants to discuss all this in depth the filmscanners 
list still exists, but there hasn't been a message for months about this 
now antique/mature technology. Send an email to listserver@... 
with 'subscribe filmscanners' as the subject to join. Or have a look 
around the (partial) archives at 
http://www.mail-archive.com/filmscanners@...
-- 
Regards

Tony Sleep
http://tonysleep.co.uk (aka www.halftone.co.uk)