Digital BW, The Print

Bill,

I understand what you are saying. But, I believe that I am infact locking
the scanner dpi setting so the scanner is "forced" to scan at an optical
resolution.

When I asked Howtek about this issue they told me that utilizing different
apertures for scanning and micro-stepping sampling, you will get a scan at a
native resolution without interpolation. The exception would be if the final
output size exceeds the maximum scan resolution of the scanner.

So infact, if one "locks" or selects an optical scan resolution and selects
an outpuit size that keeps the final scan size below 4000 dpi the scan
should still be an optical resolution scan. In addition, I was told that if
you select a resolution that is not an optical resolution, the scanner will
normally automatically scan at the next higher optical resolution and then
downsize the file thereby avoiding upward interpolation.

When setting the resolution for a scan on a Howtek drum scanner what the
user is actually setting is the "spatial" resolution. The higher the spatial
resolution the bigger the file. Optical resolution is set by the aperture on
the scanner. Optical resolution is expressed as the number of dpi that can
be discriminated, or how fine in detail each pixel is.  The wider the
aperture, the softer the image.

So for example, my original is 4"x5". I set the Q-Factor to 1.5 with a line
screen of 205. I set the desired Output size to 20"x25". Silverfast comes
back and sets the dpi at 308 (An Optical Resolution) and a file size of
90.29mb for a 16 bit grayscale image. Should I set the line screen to 157,
the resolution is set to 236, also an optical resolution. Now conversely,
sshould I set the linescreen to 150, Silverfast sets the scanner to a dpi of
225 (which is not an optical resolution) and a file size of 47.8mb. However,
according to Howtek, the scanner will scan at 236dpi (which is an optical
resolution) and then downsize the file so that no interpolation is
performed.

Now of course I may be completely wrong. If so, I am ok with that, but this
is my understanding of how this stuff works. As far as the two scans I
posted. The 4000 dpi scan will in fact appear to be sharper bue to the fact
that the scanner is using a smaller aperture. And as Howtek states, the
smaller tha aperture the sharper the detail discriminated in each pixel,
thus the greater visual presence of grain.

On another note, one of the interesting features of Silverfast is the
automatic calculation of optimal scan resolution. When the Q-Factor is set
to 1.5, all you have to do is input the desired output line screen and the
required output size and Silverfast will automatically set the optimal scan
resolution.

Mike

----- Original Message -----
From: "Bill Morse" <willym@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Saturday, April 06, 2002 12:41 PM
Subject: Re: [Digital BW] Scanning for print size: was Re: The 7...(Yadda,
Yadda)


> Mike, first I'd like to say that I am only stating my *understanding* of
> these issues- that is, I think I'm right but I'd be happy to be shown
> otherwise.
>
> Howtek says they scan at a specific dpi and adjust the aperture and drum
> speed accordingly. That's correct, but they're not referring to the print
> DPI, rather the scan or negative dpi, correct.
>
> Actually, it's only partially correct- that is, it only applies when you
> have locked the DPI settings so that the scanner is forced to one of the
> listed optical resolutions.  If you unlock the settings, the scanner will
> output any DPI you want- however, as I noted, it will do so by rezzing up
or
> down (to be truthful, I think it rezzes down, but I'm not sure.)
>
> Bottom line, as I said before, I think you are replacing scan resolution
for
> print resolution, and in the interests of lowered grain, I think you are
> just getting less resolution and more interpolation.  I looked at the two
> scans you posted (was it to the scan list?) and while one certainly had
less
> grain, what jumped out at me was that it was just much less sharp, and had
> less detail overall.
>
> It seems a shame to go through seven stages for image perfection, and then
> throw away some of the information by not using the full capabilities of
> your scanner.
>
> As I said above, this is what I *think* is happening...
>
> Bill
>
> on 4/6/02 8:15 AM, Michael Kravit wrote:
>
> Bill,
>
> You may be right but when I called Howtek they did not indicate that that
is
> the case. They publish a list of the optical resolutions for the drum
> scanner. Basically, they use a combination of drum speed, step size, and
> aperture size to obtain these rezolutions. Sol if what I understand they
are
> doing is the PMT scans at a specific dpi ie: 308dpi and the drum speed and
> x-axis movements are adjusted for the physical size of the negative.
>
> Why else would they publish such a list?
>
> Mike
>
>
> ----- Original Message -----
> From: "Bill Morse" <willym@...>
> To: <DigitalBlackandWhiteThePrint@yahoogroups.com>; "Julian Thomas"
> <julianthomas@...>
> Sent: Friday, April 05, 2002 7:21 PM
> Subject: [Digital BW] Scanning for print size: was Re: The 7... (Yadda,
> Yadda)
>
>
> > Mike, this has come up before, and I'm still unclear how you accomplish
> both
> > the below and scan at the native resolution of the scanner.  Basically,
I
> > think you are putting the DPI of the final print above the scan quality.
> >
> > If you are scanning a 4x5  to print at ~20x24 @300 DPI, you need a file
> with
> > pixel dimensions of ~6000x7200; therefor you need to scan the 4x5 @
~1500
> > DPI.  But you can't if you are scanning w/ native resolution only!  You
> > either have to scan @ 1333 DPI or @ 2000 DPI if you want native
> resolution.
> > If you force the scanner to scan @ 1500 DPI, I believe it will actually
> scan
> > @2000 DPI and rez down from there. (I think this is actually the source
of
> > what you describe as scans with less apparent grain)
> >
> > The opposite, scanner-centric process, would be to scan at the next
higher
> > scanner setting than you think you'll need, i.e. 2000 DPI, yielding an
> > 8000x10000 pixel file, and then print to 20x24 at ~400 DPI.  There are
> many
> > grain -reducing techniques that, combined with this approach, I believe
> > result in  prints with higher definition without increased grain.
> >
> > (Are your 15 minutes up yet)  ;^)
> >
> > Bill Morse
> > PhotoProspect
> > Cambridge, MA 02139
> >
> >
> >
> > ----- Original Message -----
> > From: "Michael Kravit" <michael.kravit@...>
> > To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> > Sent: Saturday, April 06, 2002 12:46 AM
> > Subject: Re: [Digital BW] The 7 Truths of Digital Printing!
> >
> >
> > > Julian,
> > >
> > > I scan to a final size of 20"x24" or so. That way 99% of what I print
> will
> > > be smaller. If I must rez up, I do so with Genuine Fractals.
> > >
> > > Mike
> > >
> > >
> > > ----- Original Message -----
> > > From: "Julian Thomas" <julianthomas@...>
> > > To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
> > > Sent: Friday, April 05, 2002 2:20 PM
> > > Subject: Re: [Digital BW] The 7 Truths of Digital Printing!
> > >
> > >
> > > > Mike, try it - I swear by it. It makes even my haulage neg.
printable!
> > BTW
> > > > you mention scanning at  final output dpi rather than the full
optical
> > > res.
> > > > How do you resize, or do you scan multiple copies?
> > > >
> > > > Julian
> > >
> > >
> > >
> > >
> > > Please visit the Group Homepage to check the Files, Bookmarks, Polls
and
> > other resources as they are often being updated. The page is at:
> > >
> > > http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint
> > >
> > > Please follow these basic guidelines:
> > > - Include your full name with your message.
> > > - Include the address of your website, if you have one.
> > > - As threads develop, trim off excess portions of earlier messages to
> keep
> > them short.
> > > - As the topic of a thread changes remember to change the subject
> header.
> > > - Good manners are required at all time. No personal attacks or
> "flames."
> > > - Complete your Yahoo profile.
> > > - Before posting a question, search the message archives and the
various
> > resources on the homepage.
> > >
> > >
> > >
> > >
> > > Your use of Yahoo! Groups is subject to
> http://docs.yahoo.com/info/terms/
> > >
> > >
> > >
> >
> >
> > Yahoo! Groups Sponsor ADVERTISEMENT
> >
> > Please visit the Group Homepage to check the Files, Bookmarks, Polls and
> > other resources as they are often being updated. The page is at:
> >
> > http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint
> >
> > Please follow these basic guidelines:
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> > - As threads develop, trim off excess portions of earlier messages to
keep
> > them short.
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header.
> > - Good manners are required at all time. No personal attacks or
"flames."
> > - Complete your Yahoo profile.
> > - Before posting a question, search the message archives and the various
> > resources on the homepage.
> >
> >
> >
> >
> > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service
> > <http://docs.yahoo.com/info/terms/> .
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> > Please visit the Group Homepage to check the Files, Bookmarks, Polls and
> other resources as they are often being updated. The page is at:
> >
> > http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint
> >
> > Please follow these basic guidelines:
> > - Include your full name with your message.
> > - Include the address of your website, if you have one.
> > - As threads develop, trim off excess portions of earlier messages to
keep
> them short.
> > - As the topic of a thread changes remember to change the subject
header.
> > - Good manners are required at all time. No personal attacks or
"flames."
> > - Complete your Yahoo profile.
> > - Before posting a question, search the message archives and the various
> resources on the homepage.
> >
> >
> >
> >
> > Your use of Yahoo! Groups is subject to
http://docs.yahoo.com/info/terms/
> >
> >
>
>
> Yahoo! Groups Sponsor ADVERTISEMENT
>
> Please visit the Group Homepage to check the Files, Bookmarks, Polls and
> other resources as they are often being updated. The page is at:
>
> http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint
>
> Please follow these basic guidelines:
> - Include your full name with your message.
> - Include the address of your website, if you have one.
> - As threads develop, trim off excess portions of earlier messages to keep
> them short.
> - As the topic of a thread changes remember to change the subject header.
> - Good manners are required at all time. No personal attacks or "flames."
> - Complete your Yahoo profile.
> - Before posting a question, search the message archives and the various
> resources on the homepage.
>
>
>
>
> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service
> <http://docs.yahoo.com/info/terms/> .
>
>
>
>
> [Non-text portions of this message have been removed]
>
>
>
> Please visit the Group Homepage to check the Files, Bookmarks, Polls and
other resources as they are often being updated. The page is at:
>
> http://groups.yahoo.com/group/DigitalBlackandWhiteThePrint
>
> Please follow these basic guidelines:
> - Include your full name with your message.
> - Include the address of your website, if you have one.
> - As threads develop, trim off excess portions of earlier messages to keep
them short.
> - As the topic of a thread changes remember to change the subject header.
> - Good manners are required at all time. No personal attacks or "flames."
> - Complete your Yahoo profile.
> - Before posting a question, search the message archives and the various
resources on the homepage.

>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>

Hi Mike,

Two points-
First, on the issue of "microstepping" to achieve any desired resolution
below 4000 DPI:  If that is true, then why bother "locking" into "optical
resolution" at all (below 4000DPI)?  Can you really get, 305 DPI, or 3765
DPI, or 3888.8 DPI?  What is really happening (as you alluded to, and as I
suggested earlier) is that the scanner is scanning at the next higher
resolution and then interpolating down- but interpolating down, while not as
"fuzzy" as up-sampling, still leads to softening of the image.

2nd, and more importantly, the issue of the DPI of the image.

"I set the Q-Factor to 1.5 with a line screen of 205...  I set the desired
Output size to 20"x25"...Silverfast ... sets the dpi at 308."

Yes, 205 x 1.5= ~308 DPI-  But Mike, that's the DPI of your print @ 20x25,
not your scan!  

In PS, open a new file, 20x25, 308 DPI- at 8 bit it's 45.3 MB; at 16, as you
say, it's 90.3 MB.  But more importantly, it's 6160 x 7700 **pixels**.  To
get a file of 6160 x 7700 pixels from a 4x5, you have to scan at 1540 DPI-
and that in fact is what you are scanning at, only you are really scanning
at 2000 DPI and Silverfast is interpolating down, either by averaging pixels
or throwing away pixels.  In either case, why not just scan at 2000 DPI, no
interpolation, and then print at the resultant PPI, in this case at 400 PPI?

Lastly (did I say there were 2 points :^)  on Silverfast, Q-factors, and
"optimal Scan resolution".  As I understand it, all of this comes from
pre-press offset scanning; that is the derivation of the "1.5 times
linescreen" resolution.  I don't believe it has any relevance to inkjet
printing with Epson's.  Some people maintain that divisibles (?) of Epson's
1440 DPI give the best results- in which case you would try for 180, 240,
360, 540, or 720 DPI.  Others point out that if you achieve that by
interpolating up or down, you are adding softness.  Paul has shown that
above (I think it was) 540 DPI, there is no increase in measurable
sharpness, and that 360 DPI is for almost all purposes equally as good.  In
my scanning for print, I try to achieve something close to 360 DPI at my
largest anticipated print size; beyond that, I let the Epson driver do the
math.

Your prints are still better than mine, dammit, but that's another issue
altogether!

Bill

on 4/6/02 4:48 PM, Michael Kravit wrote:

Bill,

I understand what you are saying. But, I believe that I am in fact locking
the scanner dpi setting so the scanner is "forced" to scan at an optical
resolution.

When I asked Howtek about this issue they told me that utilizing different
apertures for scanning and micro-stepping sampling, you will get a scan at a
native resolution without interpolation. The exception would be if the final
output size exceeds the maximum scan resolution of the scanner.


... So infact, if one "locks" or selects an optical scan resolution and
selects
an outpuit size that keeps the final scan size below 4000 dpi the scan
should still be an optical resolution scan. In addition, I was told that if
you select a resolution that is not an optical resolution, the scanner will
normally automatically scan at the next higher optical resolution and then
downsize the file thereby avoiding upward interpolation.

... So for example, my original is 4"x5". I set the Q-Factor to 1.5 with a
line screen of 205. I set the desired Output size to 20"x25". Silverfast
comes
back and sets the dpi at 308 (An Optical Resolution) and a file size of
90.29mb for a 16 bit grayscale image. Should I set the line screen to 157,
the resolution is set to 236, also an optical resolution. Now conversely,
sshould I set the linescreen to 150, Silverfast sets the scanner to a dpi of
225 (which is not an optical resolution) and a file size of 47.8mb. However,
according to Howtek, the scanner will scan at 236dpi (which is an optical
resolution) and then downsize the file so that no interpolation is
performed.

Now of course I may be completely wrong. If so, I am ok with that, but this
is my understanding of how this stuff works. As far as the two scans I
posted. The 4000 dpi scan will in fact appear to be sharper bue to the fact
that the scanner is using a smaller aperture. And as Howtek states, the
smaller tha aperture the sharper the detail discriminated in each pixel,
thus the greater visual presence of grain.

On another note, one of the interesting features of Silverfast is the
automatic calculation of optimal scan resolution. When the Q-Factor is set
to 1.5, all you have to do is input the desired output line screen and the
required output size and Silverfast will automatically set the optimal scan
resolution.

Mike

----- Original Message -----
From: "Bill Morse" <willym@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Saturday, April 06, 2002 12:41 PM
Subject: Re: [Digital BW] Scanning for print size: was Re: The 7...(Yadda,
Yadda)


Mike, first I'd like to say that I am only stating my *understanding* of
these issues- that is, I think I'm right but I'd be happy to be shown
otherwise.

Howtek says they scan at a specific dpi and adjust the aperture and drum
speed accordingly. That's correct, but they're not referring to the print
DPI, rather the scan or negative dpi, correct.

Actually, it's only partially correct- that is, it only applies when you
have locked the DPI settings so that the scanner is forced to one of the
listed optical resolutions.  If you unlock the settings, the scanner will
output any DPI you want- however, as I noted, it will do so by rezzing up
or
down (to be truthful, I think it rezzes down, but I'm not sure.)

Bottom line, as I said before, I think you are replacing scan resolution
for
print resolution, and in the interests of lowered grain, I think you are
just getting less resolution and more interpolation.  I looked at the two
scans you posted (was it to the scan list?) and while one certainly had
less
grain, what jumped out at me was that it was just much less sharp, and had
less detail overall.

It seems a shame to go through seven stages for image perfection, and then
throw away some of the information by not using the full capabilities of
your scanner.

As I said above, this is what I *think* is happening...

Bill

on 4/6/02 8:15 AM, Michael Kravit wrote:

Bill,

You may be right but when I called Howtek they did not indicate that that
is
the case. They publish a list of the optical resolutions for the drum
scanner. Basically, they use a combination of drum speed, step size, and
aperture size to obtain these rezolutions. Sol if what I understand they
are
doing is the PMT scans at a specific dpi ie: 308dpi and the drum speed and
x-axis movements are adjusted for the physical size of the negative.

Why else would they publish such a list?

Mike


----- Original Message -----
From: "Bill Morse" <willym@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>; "Julian Thomas"
<julianthomas@...>
Sent: Friday, April 05, 2002 7:21 PM
Subject: [Digital BW] Scanning for print size: was Re: The 7... (Yadda,
Yadda)


Mike, this has come up before, and I'm still unclear how you accomplish
both
the below and scan at the native resolution of the scanner.  Basically,
I
think you are putting the DPI of the final print above the scan quality.

If you are scanning a 4x5  to print at ~20x24 @300 DPI, you need a file
with
pixel dimensions of ~6000x7200; therefor you need to scan the 4x5 @
~1500
DPI.  But you can't if you are scanning w/ native resolution only!  You
either have to scan @ 1333 DPI or @ 2000 DPI if you want native
resolution.
If you force the scanner to scan @ 1500 DPI, I believe it will actually
scan
@2000 DPI and rez down from there. (I think this is actually the source
of
what you describe as scans with less apparent grain)

The opposite, scanner-centric process, would be to scan at the next
higher
scanner setting than you think you'll need, i.e. 2000 DPI, yielding an
8000x10000 pixel file, and then print to 20x24 at ~400 DPI.  There are
many
grain -reducing techniques that, combined with this approach, I believe
result in  prints with higher definition without increased grain.

(Are your 15 minutes up yet)  ;^)

Bill Morse
PhotoProspect
Cambridge, MA 02139



----- Original Message -----
From: "Michael Kravit" <michael.kravit@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Saturday, April 06, 2002 12:46 AM
Subject: Re: [Digital BW] The 7 Truths of Digital Printing!


Julian,

I scan to a final size of 20"x24" or so. That way 99% of what I print
will
be smaller. If I must rez up, I do so with Genuine Fractals.

Mike


----- Original Message -----
From: "Julian Thomas" <julianthomas@...>
To: <DigitalBlackandWhiteThePrint@yahoogroups.com>
Sent: Friday, April 05, 2002 2:20 PM
Subject: Re: [Digital BW] The 7 Truths of Digital Printing!


Mike, try it - I swear by it. It makes even my haulage neg.
printable!
BTW
you mention scanning at  final output dpi rather than the full
optical
res.
How do you resize, or do you scan multiple copies?

Julian




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