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I just read Margulis' chapter on resolution and am somewhat confused
(it's one of those things you have to read multiple times, I think).
Up to now I have been scanning my 6x6 and some 35mm slides and negs at
3000-4000dpi on a Nikon LS8000 at 14-bit depth, and manipulating
mostly at full res, then downsampling to 300dpi before sending it to
my Epson 2200. According to Margulis, having a resolution too high
can soften an image, so I'm trying to find out two things:

1. Is the softening that occurs an effect of sending too much data to
the printer, and if so, wouldn't downsampling before printing correct
it, or should it be scanned at a lower resolution to begin with?

2. Where can I find a reference of starting points for optimum
scanning resolution that considers input film size, final print size,
and optimum print resolution?

Thanks for any input.

Chris

"hassy_user" <> wrote in message
news: om...
> I just read Margulis' chapter on resolution and am somewhat
> confused (it's one of those things you have to read multiple times,
> I think). Up to now I have been scanning my 6x6 and some
> 35mm slides and negs at 3000-4000dpi on a Nikon LS8000 at
> 14-bit depth, and manipulating mostly at full res,

So far, you've done well.

> then downsampling to 300dpi before sending it to my Epson
> 2200.

That is not optimal. The 2200 (like most desktop Epsons) internally
dithers based on a 720ppi image. If the ppi for the output size
requested is different, the printer driver will interpolate to 720
ppi. In your case, it will more than quadruple the number of pixels
you offered it. Interpolation will not help resolution.

> According to Margulis, having a resolution too high can soften
> an image, so I'm trying to find out two things:
>
> 1. Is the softening that occurs an effect of sending too much
> data to the printer, and if so, wouldn't downsampling before
> printing correct it, or should it be scanned at a lower resolution
> to begin with?

As stated above, only down-sample to 720 ppi at output size. Then
sharpen the result, you can visually oversharpen a bit, because there
will be losses in the printing process. Always judge the amount of
sharpening at 100% zoom level in the photoeditor.

> 2. Where can I find a reference of starting points for optimum
> scanning resolution that considers input film size, final print
size,
> and optimum print resolution?

Scanning film at the highest native resolution will reduce apparent
graininess, so by all means keep doing it as you are. You can improve
the downsampling quality by applying a little blur before
downsampling. The amount of blur needed depends on the amount of
downsampling. That will also help reducing apparent graininess,
instead of increasing it due to grain-aliasing.
http://www.xs4all.nl/~bvdwolf/main/f...own_sample.htm
http://www.xs4all.nl/~bvdwolf/main/f...e/example1.htm
Print resolution, as stated should in your case be 720 ppi after
resampling.

Grain aliasing is explained here:
http://www.photoscientia.co.uk/Grain.htm

Bart

>From: (hassy_user)

>I just read Margulis' chapter on resolution and am somewhat confused
>
>Up to now I have been scanning my 6x6 and some 35mm slides and negs at
>3000-4000dpi on a Nikon LS8000 at 14-bit depth, and manipulating
>mostly at full res, then downsampling to 300dpi before sending it to
>my Epson 2200. According to Margulis, having a resolution too high
>can soften an image, so I'm trying to find out two things:
>
>1. Is the softening that occurs an effect of sending too much data to
>the printer, and if so, wouldn't downsampling before printing correct
>it, or should it be scanned at a lower resolution to begin with?

Dan is a member of the "scan for the target output" club, which is the way most
book and magazine publishers and many advertising agencies work. They rarely
print large prints (especially magazines and books) and don't spend a lot of
time fine-tuning each image, as a general rule.

The other side of the coin is the "scan once, output many" club which feels
it's best to scan at high rez, do all your prep work on a master file (which is
what you're doing) and downsample and sharpen to various output sizes ranging
from large fine art prints to tiny web thumbnails. Here's a good explanation
of the theory from a fine art lab I've used, West Coast Imaging ...
http://www.westcoastimaging.com/wci/.../scanonce.html The key
to doing this well is to know how to downsample well and how to use USM in a
variety of situations, typically with film using edge sharpening or something
similar.

You should be able to run a test yourself with the 8000 and see if downsampling
works for you ... just scan at the native rez (4,000 dpi) and downsample to say
360 ppi for a decent sized print and print it. Also scan at the exact rez for
this size print and print directly from that one too without downsampling ...
if you're printing 10x10" @ 360 ppi for example you need 3600 pixels/side so
would scan at roughly 1650 dpi (the Nikon software lets you set this exactly).

See what looks best, the 10x10" print at 1650 or the 4000 dpi scan downsampled.
Keep in mind Dan has access to much better scanners than your 8000 (which is
what I use too and he may get a better result with his 1650 dpi scan than
you or I with the Nikon. The Nikon will still scan internally at 4,000 dpi and
then downsample with its software ... can you do this better in Photoshop
yourself?

>2. Where can I find a reference of starting points for optimum
>scanning resolution that considers input film size, final print size,
>and optimum print resolution?

You can work backwards once you know the optimal printer ppi and the desired
print size (multiply the ppi x the print dimensions to get the pixel count and
divide this by the size of the film to get the scan rez), but of course the
main problem is that you'll get a different target scan rez for each print size
and for each printer ppi. No problem if you're scanning once for a magazine
article but a hassle if you think you'll print the same file yourself at
various sizes or need even smaller images for the web.

If you want to see what a real digital ace can do with the "scan once and
resize" flow look at Bill Atkinson's work. He shoots Velvia with a Hassy and
scans at 5,000 dpi with a Tango drum, then resizes these files for anything
from a 24x24" fine art print at 360 ppi to thumbnails for the web that are
100x100 pixels ... http://www.billatkinson.com/CatalogIndex.html

Bill

Bill Hilton wrote:


Hi...

<much snipped>

> You should be able to run a test yourself with the 8000 and see if downsampling
> works for you ... just scan at the native rez (4,000 dpi) and downsample to say
> 360 ppi for a decent sized print and print it. Also scan at the exact rez for
> this size print and print directly from that one too without downsampling ...
> if you're printing 10x10" @ 360 ppi for example you need 3600 pixels/side so
> would scan at roughly 1650 dpi (the Nikon software lets you set this exactly).

<more snipped>

For what it's worth, I did this test using many
variations... about 20 prints worth. (Kodak machine
in the mall type prints)

Blind tests for which was better was always extremely
close. Testers (included print machine operator, the
subject herself, neighbors and friends) after long
consideration always concluded that the "big" scan,
untouched by PS or PSP, was the best.

Ken

(hassy_user) wrote in message news:<. com>...
> I just read Margulis' chapter on resolution and am somewhat confused
> (it's one of those things you have to read multiple times, I think).
> Up to now I have been scanning my 6x6 and some 35mm slides and negs at
> 3000-4000dpi on a Nikon LS8000 at 14-bit depth, and manipulating
> mostly at full res, then downsampling to 300dpi before sending it to
> my Epson 2200. According to Margulis, having a resolution too high
> can soften an image, so I'm trying to find out two things:
>
> 1. Is the softening that occurs an effect of sending too much data to
> the printer, and if so, wouldn't downsampling before printing correct
> it, or should it be scanned at a lower resolution to begin with?
>
> 2. Where can I find a reference of starting points for optimum
> scanning resolution that considers input film size, final print size,
> and optimum print resolution?
>
> Thanks for any input.
>
> Chris

Thanks Bart, Bill, and Ken for the thoughtful responses. Bill and
Bart, you apparently differ on the recommended output ppi (360 vs
720). Will there be a visible difference, however subtle, in choosing
one over the other?

Chris

"hassy_user" <> wrote in message
news: om...
SNIP
> Bill and Bart, you apparently differ on the recommended output
> ppi (360 vs 720). Will there be a visible difference, however
> subtle, in choosing one over the other?

Depends on the image processing done to the final sized file, and
whether it had enough resolution to begin with. Assuming the file has
enough native resolution, the 720 ppi version will allow to enhance
edge contrast more accurately. The resulting output will look better
in that case.

If you use a dedicated print program like Qimage, life becomes even
easier because it takes care of it automagically (including profile
conversion and optimization of paper used), without altering the
original file.

Bart

"Bart van der Wolf" <> wrote in message news:<41769feb$0$78753$>...
> "hassy_user" <> wrote in message
> news: om...
> SNIP
> > Bill and Bart, you apparently differ on the recommended output
> > ppi (360 vs 720). Will there be a visible difference, however
> > subtle, in choosing one over the other?
>
> Depends on the image processing done to the final sized file, and
> whether it had enough resolution to begin with. Assuming the file has
> enough native resolution, the 720 ppi version will allow to enhance
> edge contrast more accurately. The resulting output will look better
> in that case.
>
> If you use a dedicated print program like Qimage, life becomes even
> easier because it takes care of it automagically (including profile
> conversion and optimization of paper used), without altering the
> original file.
>
> Bart

Thanks Bart. I save all of my raw scans so I'll do a comparison at
both print resolutions with a minimum of processing, and USM after the
final image size is set. I'm curious to see if the difference shows
up at 10"x10".

Does Qimage offer any advantage besides convenience? If I already
know how to soft proof and color manage, do I need it?

Thanks.

Chris

"hassy_user" <> wrote in message
news: om...
SNIP
> Does Qimage offer any advantage besides convenience? If I
> already know how to soft proof and color manage, do I need
> it?

That also depends, on your output requirements. A common user comment
is that when comparing the same image output from Photoshop and Qimage
side-by-side, usually results in higher quality for Qimage. But again,
it depends on what you start with, and what the output size is.

The colors will be exactly the same, as both Photoshop and Qimage are
color managed applications, but in general, when the printer driver
causes a need to interpolate the image data, Qimage output quality
always wins. At (very) large output sizes Qimage excels.
The workflow benefits become apparent when you e.g. need multiple,
different sized, versions of an image on the same page, or if you want
to produce contact sheets, or different cropped versions of a file.
All those different sizes are derived from the original, which remains
unaltered.

Bart

"Bart van der Wolf" <> wrote in message news:<417ccc8b$0$37789$>...
> "hassy_user" <> wrote in message
> news: om...
> SNIP
> > Does Qimage offer any advantage besides convenience? If I
> > already know how to soft proof and color manage, do I need
> > it?
>
> That also depends, on your output requirements. A common user comment
> is that when comparing the same image output from Photoshop and Qimage
> side-by-side, usually results in higher quality for Qimage. But again,
> it depends on what you start with, and what the output size is.
>
> The colors will be exactly the same, as both Photoshop and Qimage are
> color managed applications, but in general, when the printer driver
> causes a need to interpolate the image data, Qimage output quality
> always wins. At (very) large output sizes Qimage excels.
> The workflow benefits become apparent when you e.g. need multiple,
> different sized, versions of an image on the same page, or if you want
> to produce contact sheets, or different cropped versions of a file.
> All those different sizes are derived from the original, which remains
> unaltered.
>
> Bart

Thanks. I'll see if there's a trial version and test it. If I'm
printing at the printer's native resolution (720ppi), then there
shouldn't be a difference, right?

Chris

"hassy_user" <> wrote in message
news: om...
SNIP
> Thanks. I'll see if there's a trial version and test it. If I'm
> printing at the printer's native resolution (720ppi), then there
> shouldn't be a difference, right?

If you supply 720 meaningful pixels for each output inch, there will
still be a difference. This is due to Qimage compensating for the
losses incurred in the (inkjet) printing process. The amount of
compensation is user adjustable, and can be set to zero. When changed
from its default to zero, then there should be no difference.

There is a time limited demo version that only processes a few images
per session available at http://www.ddisoftware.com/qimage/ . There
are examples for common tasks in the help file, and there is a Yahoo
forum for support.

Bart