P3D Re: Scanrom 4E Results

[Dylan The Hippy Wabbit <spacey@xxxxxxxxxxxxx>]

I sent this on Friday, but it didn't make it.  2nd try.

Hi,

Allen French wrote about his scanner:-

>  I mostly used the highest optical resolution, 400 dpi, but I also tried
>a few at higher software interpolated resolutions (up to 4800dpi
>claimed). I really didn't see much ,if any improvement over the 400 dpi.

No you wouldn't.  As a rule of thumb I don't interpolate more than about
1.5 times the optical resolution.  Run a sharpen filter over the scan next
and you *might* get detail that you wouldn't otherwise.  You certainly
can't interpolate a photo to 12 times the optical resolution, whatever the
advertising suits claim.

To be uncharacteristically fair to the suits I understand that massive
interpolation is useful for scanning text though.

>I did try to improve the hue and contrast with software, but it may not
>have helped the resolution.

Wouldn't hurt it either.  Not as long as you don't go mad and push
everything into the shadows or highlights.  Your software might have a
command to show you a histogram of the contrast.  If it already fills the
range don't increase the contrast further.

>You can see a few samples at www.public.asu.edu/~icsaff/scanrom.html .
>The clickable small images were the 400 dpi, and the larger cross-eyed 
>pair below is 1600.

Allen, your web page slowed my PC to a crawl.  Decoding and then rescaling
those big images (especially the last) took up all my RAM and set the hard
drive thrashing away like a sadist at an orgy.  Must be costing your web
server lots of bandwidth too.

May I suggest that instead you produce smaller copies of the pictures to
use in the IMG tag?  No need to scan again, your software should have a
resize or resample command.  Then the reference to your picture could
read:-

<A HREF="thai9lrl.jpg"><IMG SRC="thai9sml.jpg" ALT="thai9lrl.jpg"</A>

That way the large version is only sent if requested, saving time and
resources all round.

Hope this helps

Dave Spacey


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Walk tall, walk straight,
Spit the world right in the eye.

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