Digital BW, The Print

Austin, A friend just purchased an epson 2450.  After your advice concerning the native resolution for scanning with a Umax MirageII, which was right on, do you happen to know what the native resolution for the epson would be?
Thanks again
David Aschkenas

Hi David,

Easy enough to find...

http://www.epson.com

click on "Canada/United States"
click on "Scanners"
click on "Perfection 2450 PHOTO Scanner"

And you can either read what they say there, or get even more information by
downloading the .pdf spec sheet....or click on "See Detailed List..."

;-)

> -----Original Message-----
> From: daschkenas@... [mailto:daschkenas@...]
> Sent: Thursday, June 06, 2002 4:27 PM
> To: DigitalBlackandWhiteThePrint@yahoogroups.com
> Subject: Re: [Digital BW] Re: Native resolution for scanning
>
>
> Austin, A friend just purchased an epson 2450.  After your advice
> concerning the native resolution for scanning with a Umax
> MirageII, which was right on, do you happen to know what the
> native resolution for the epson would be?
> Thanks again
> David Aschkenas

Austin, I checked out the info on the epson site about the 2450, and read that the resolution is 2400, but no mention of NATIVE RESOLUTION, Is the answer to the question 2400?
David

> Austin, I checked out the info on the epson site about the 2450, and read that
the resolution is 2400, but no mention of NATIVE RESOLUTION, Is the answer to
the question 2400?
> David

I'm not Austin, but I'll speak up. Yes, you got the right answer.

Think of native resolution as the highest resolution the scanner can do without
interpolation (where new pixels are 'created' by the software).

The Epson 2450 can scan at 2400 x 4800 samples per inch. Imagine a row of
sensors spaced at 1/2400 inch, which steps across the original at 1/4800 inch
intervals. But your image editing program (Photoshop or whatever) can't deal
with pixels that are not on a square grid.

To use the 2400 x 4800 scan the scanner software has to interpolate to 4800 x
4800, by 'inventing' the missing pixels by averaging the neighbouring pixels. If
you tell the scanner to sample at 2400 x 2400 the sensors step across the
original at 1/2400 inch intervals, and every pixel is 'real'. Native resolution.

Peter Marquis-Kyle

> Austin, I checked out the info on the epson site about the 2450, 
> and read that the resolution is 2400, but no mention of NATIVE 
> RESOLUTION, Is the answer to the question 2400?
> David

Hi David,

On the page linked to by "See Detailed List >>" it says:

"Optical Resolution  2400 dpi"

which is the same as "native" resolution.  So, yes, the answer is 2400.

Regards,

Austin

BTW => Native resolution = OPTICAL resolution

  -----Original Message-----
  From: Peter Marquis-Kyle [mailto:petermk@...]
  Sent: Thursday, June 06, 2002 7:04 PM
  To: DigitalBlackandWhiteThePrint@yahoogroups.com
  Subject: Re: [Digital BW] Re: Native resolution for scanning


  > Austin, I checked out the info on the epson site about the 2450, and
read that
  the resolution is 2400, but no mention of NATIVE RESOLUTION, Is the answer
to
  the question 2400?
  > David

  I'm not Austin, but I'll speak up. Yes, you got the right answer.

  Think of native resolution as the highest resolution the scanner can do
without
  interpolation (where new pixels are 'created' by the software).

  The Epson 2450 can scan at 2400 x 4800 samples per inch. Imagine a row of
  sensors spaced at 1/2400 inch, which steps across the original at 1/4800
inch
  intervals. But your image editing program (Photoshop or whatever) can't
deal
  with pixels that are not on a square grid.

  To use the 2400 x 4800 scan the scanner software has to interpolate to
4800 x
  4800, by 'inventing' the missing pixels by averaging the neighbouring
pixels. If
  you tell the scanner to sample at 2400 x 2400 the sensors step across the
  original at 1/2400 inch intervals, and every pixel is 'real'. Native
resolution.

  Peter Marquis-Kyle


[Non-text portions of this message have been removed]

Thanks you, Austin & Peter.

Peter,

From the Epson info that I have read, the 2450 has a 6-line alternated
sensor with 61,000 sensor elements. So the sensor elements are presumably
spaced at 1/1200 inch with alternate lines staggered to fill in the missing
elements by interpolation. You can't escape interpolation it seems, even at
optical or native resolutions!

Or have I misread the info? Austin will know!

Bob Frost.

----- Original Message -----
From: "Peter Marquis-Kyle" <petermk@...>

> The Epson 2450 can scan at 2400 x 4800 samples per inch. Imagine a row of
> sensors spaced at 1/2400 inch, which steps across the original at 1/4800
inch
> intervals. But your image editing program (Photoshop or whatever) can't
deal
> with pixels that are not on a square grid.
>
> To use the 2400 x 4800 scan the scanner software has to interpolate to
4800 x
> 4800, by 'inventing' the missing pixels by averaging the neighbouring
pixels. If
> you tell the scanner to sample at 2400 x 2400 the sensors step across the
> original at 1/2400 inch intervals, and every pixel is 'real'. Native
resolution.

> Peter,
>
> From the Epson info that I have read, the 2450 has a 6-line alternated
> sensor with 61,000 sensor elements. So the sensor elements are presumably
> spaced at 1/1200 inch with alternate lines staggered to fill in
> the missing
> elements by interpolation. You can't escape interpolation it
> seems, even at
> optical or native resolutions!
>
> Or have I misread the info? Austin will know!
>
> Bob Frost.
>

Hi Bob,

Well, sorry to disappoint you, but I don't know!  If it's interpolated, then
it isn't really "optical" resolution...  The spec sheet says "Color Matrix
CCD line sensor"...what ever that is...and it does also say "Optical
Resolution 2400 dpi", which, if what you say is true, their spec isn't
accurate IMO.  I'll see if I can find out what sensor it actually uses, and
see if I can get a spec on it.

But, for $400 it's a very amazing scanner...

Regards,

Austin

Bob Frost wrote

> From the Epson info that I have read, the 2450 has a 6-line alternated
> sensor with 61,000 sensor elements. So the sensor elements are presumably
> spaced at 1/1200 inch with alternate lines staggered to fill in the missing
> elements by interpolation. You can't escape interpolation it seems, even at
> optical or native resolutions!

...and Alan Zinn wrote

> In the case of the E2450 I have not seen an improvement above 1800 -  I don't
> know if that is "native" or not. For what it's worth I have a review of it
> on my web page.

Which all goes to show that, when I tried to explain 'native resolution' I
assumed too much.

I don't quite agree with what Bob says, though it's a small quibble. In scanners
with multiple lines of staggered sensors I think the quality might be degraded
by each sensor sampling too large an area of the original, rather than by
interpolation.

Whatever the theory, Alan's practical observation of 'no improvement above 1800'
is the interesting one -- that is, that results are better than you'd get with a
single 1200 spi sensor, but not as good as a 'real' 2400 spi one.

Still, in comparison with its elders and betters, the Epson 2450 sounds like
terrific value for money. I don't regret renouncing the darkroom, but maybe I
shouldn't have got rid of my 4x5 camera....

Peter Marquis-Kyle

Austin,

I shall treasure that reply and put it in a folder of its own headed "What
Austin doesn't know"!

I'm not quite sure how we got into this discussion on the B&W list (I had to
look twice to see what list we were on), but since we've started we might as
well finish:

The line I quoted is in the Product Specifications (and copied below):

      CCD 6 line alternated with 61,200 pixels CCD



61K pixels over 6 lines gives 10200 per line, which over an 8" scanning
width gives just over 1200 pixels per inch.

I seem to remember an earlier fuss because Epson was using staggered lines
of sensors and claiming higher resolution (just as Fuji do with the S1?).

It will be interesting to see what you find out.

Bob Frost.

----- Original Message -----
From: "Austin Franklin" <darkroom@...>
> Hi Bob,
>
> Well, sorry to disappoint you, but I don't know!  If it's interpolated,
then
> it isn't really "optical" resolution...  The spec sheet says "Color Matrix
> CCD line sensor"...what ever that is...and it does also say "Optical
> Resolution 2400 dpi", which, if what you say is true, their spec isn't
> accurate IMO.  I'll see if I can find out what sensor it actually uses,
and
> see if I can get a spec on it.

At 04:27 PM 6/6/2002 -0400, you wrote:
>Austin, A friend just purchased an epson 2450.  After your advice
concerning the native resolution for scanning with a Umax MirageII, which
was right on, do you happen to know what the native resolution for the epson
would be?
>Thanks again
>David Aschkenas
>

Guys,

In the case of the E2450 I have not seen an improvment above 1800 -  I don't
know if that is "native" or not. For what it's worth I have a review of it
on my web page.

AZ

Maker of Lookaround panoramic camera.
http://www.panoramacamera.us
         or
keyword.com lookaround