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Resolution for scanning slides?

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Anonymous
February 23, 2005 4:48:59 PM

Archived from groups: rec.photo.digital (More info?)

Just got my first scanner capable of scanning slides, and I'm
wondering, what resolution should I use for scanning slides
so as to neither lose data nor waste memory. Any thoughts?
Thanks for any replies.
Anonymous
February 23, 2005 7:29:04 PM

Archived from groups: rec.photo.digital (More info?)

Anthony Buckland commented courteously ...

> Just got my first scanner capable of scanning slides,
> and I'm wondering, what resolution should I use for
> scanning slides so as to neither lose data nor waste
> memory. Any thoughts?

Hi, Anthony.

My limited experience with neg/slide scanning for 35mm
worked best with a minimum DPI of 1800, preferably 2500.

This will give image sizes from 2000 x 1600 to maybe 2700
x 2200. That's pretty large, of course, and whether you
need to go to 2500 or not depends a lot on the condition
of your slides, e.g., exposure, film grain,
sharpness/detail from your camera and developer, etc.

Then, after post-processing to taste, reduce to the
finish size you'd like and save to your favorite format.
The finish size you choose depends heavily on if you want
to just display your digitized scans on-screen or print
them at as high quality as possible, or both.

Err on the side of larger; you can always reduce in steps
but it is impossible to significantly enlarge without
loss of image quality.

--
ATM, aka Jerry
Anonymous
February 23, 2005 7:29:05 PM

Archived from groups: rec.photo.digital (More info?)

All Things Mopar wrote:

>Anthony Buckland commented courteously ...
>
>
>
>>Just got my first scanner capable of scanning slides,
>>and I'm wondering, what resolution should I use for
>>scanning slides so as to neither lose data nor waste
>>memory. Any thoughts?
>>
>>
>
>Hi, Anthony.
>
>My limited experience with neg/slide scanning for 35mm
>worked best with a minimum DPI of 1800, preferably 2500.
>
>This will give image sizes from 2000 x 1600 to maybe 2700
>x 2200. That's pretty large, of course, and whether you
>need to go to 2500 or not depends a lot on the condition
>of your slides, e.g., exposure, film grain,
>sharpness/detail from your camera and developer, etc.
>
>Then, after post-processing to taste, reduce to the
>finish size you'd like and save to your favorite format.
>The finish size you choose depends heavily on if you want
>to just display your digitized scans on-screen or print
>them at as high quality as possible, or both.
>
>Err on the side of larger; you can always reduce in steps
>but it is impossible to significantly enlarge without
>loss of image quality.
>
>
>
Thanks, just the information I needed. To answer your second-last
paragraph,
I'll want to do both, a slide slow on a monitor, with printing of selected
slides, probably no larger than 4x6. The camera was fairly good for its
time,
so it sounds as though 2400 would be a good place to start experimenting.
Related resources
Anonymous
February 23, 2005 7:58:52 PM

Archived from groups: rec.photo.digital (More info?)

"Anthony Buckland" <buckland@direct.ca> wrote in message
news:bICdnY_Fe-rRZ4HfRVn-qw@look.ca...
> Just got my first scanner capable of scanning slides, and I'm
> wondering, what resolution should I use for scanning slides
> so as to neither lose data nor waste memory. Any thoughts?
> Thanks for any replies.
>

Can't do both. I would go for maximum resolution, then burn the images to
CDs.
Anonymous
February 23, 2005 11:20:58 PM

Archived from groups: rec.photo.digital (More info?)

Anthony Buckland wrote:
> Just got my first scanner capable of scanning slides, and I'm
> wondering, what resolution should I use for scanning slides
> so as to neither lose data nor waste memory. Any thoughts?
> Thanks for any replies.
>
Go here for information on scanning.
www.scantips.com

Everything you need to know about scanning.
And more.


--
Ron Hunter rphunter@charter.net
Anonymous
February 23, 2005 11:38:23 PM

Archived from groups: rec.photo.digital (More info?)

Anthony Buckland commented courteously ...

> Thanks, just the information I needed. To answer
> your second-last paragraph, I'll want to do both,
> a slide slow on a monitor, with printing of selected
> slides, probably no larger than 4x6.

Anthony, prevailing wisdom says you need about 200 PPI
(pixels per inch) to get a "quality" print, better still
the closer you get to 300 PPI. There're times when I
severely violate that "rule", because I just can't get
near that much PPI with "real" image information (e.g.,
scanning a snapshot, where you max out at 200-300, even
then, they're often soft, that's why scanning negs/slides
is superior to scanning prints).

But, if you took "200 min, 300 preferably" "rule" to get
"good" 4 x 6 prints, you'd need in the range of *only*
1200 x 800 to *maybe* 1800 x 1200. *Much* smaller than
what you would scan at.

Still, I recommend scanner at the higher DPI to get the
best of the detail in the slide, plus while some may
argue, its been my experience that scanning to 2500
pixels, then resizing down to 1280 in two steps (with
mild noise reduction and mild sharpening at the
intermediate re-size), will yield excellent results. This
is because the noise generated by film grain tends to be
"compressed" out (in layman's terms), so you don't have
apply much if any noise reduction.

So, again assuming that there's sufficient detail in your
slides, and you're saying that the camera was "fairly
good", that leaves only the quality of your slide
chemical processing (and the speed of the film, higher =
more grain = scanner noise).

So, if you think your printing needs will generally be 4
x 6, you'd probably be OK with my "standard", 1280 x 900
or there abouts. You could still print on your inkjet on
glossy 8.5 x 11 paper, just view the prints at a distance
of 2-3 feet and they'll look superb.

--
ATM, aka Jerry
Anonymous
February 24, 2005 1:20:53 AM

Archived from groups: rec.photo.digital (More info?)

On Wed, 23 Feb 2005 13:48:59 -0800, Anthony Buckland wrote:
> Just got my first scanner capable of scanning slides, and I'm
> wondering, what resolution should I use for scanning slides
> so as to neither lose data nor waste memory. Any thoughts?

Gee, it occured to me that this might be an FAQ.
Therefore, I went to the largest FAQ repository on the
web with your _exact_ Subject:

http://groups.google.co.uk/groups?as_q=Resolution%20for...

Learn to fish.
Anonymous
February 24, 2005 10:03:24 AM

Archived from groups: rec.photo.digital (More info?)

On Wed, 23 Feb 2005 21:48:59 +0000, Anthony Buckland wrote:

> Just got my first scanner capable of scanning slides, and I'm wondering,
> what resolution should I use for scanning slides so as to neither lose
> data nor waste memory. Any thoughts? Thanks for any replies.

Depends on what you want to do with the scanned images. If you are going
to see them only on the PC screen or project with a standard projector, a
resolution of 720 or 900 (allowing for some cropping during processing)
will be adequate. No much benefit for any higher resolution (i.e.,
increasing the pixel count) as the viewing software would reduce the pixel
count to fit the screen. Some slides you may like to scan at a higher
resolution if you wish to crop out a large section of the image.

For printing, higher the better.

--

Gautam Majumdar

Please send e-mails to gmajumdar@freeuk.com
Anonymous
February 24, 2005 10:53:17 AM

Archived from groups: rec.photo.digital (More info?)

You don't seem to understand what this NG is for. Try to keep a civil
tongue in your head.

The answer to the question is that it depends on the resolution of the film.
Provia 100 needs about 2400 ppi, for example. Beyond that, you just
get a better view of grain.

Graham


"drwxr-xr-x" <bit-bucket@config.com> wrote in message
news:slrnd1q0e5.7uf.bit-bucket@shell.config.com...
> Gee, it occured to me that this might be an FAQ.
> Therefore, I went to the largest FAQ repository on the
> web with your _exact_ Subject:
>
>
http://groups.google.co.uk/groups?as_q=Resolution%20for...
>
> Learn to fish.
Anonymous
February 24, 2005 12:03:32 PM

Archived from groups: rec.photo.digital (More info?)

Gautam Majumdar wrote:

> On Wed, 23 Feb 2005 21:48:59 +0000, Anthony Buckland wrote:
>
>
>>Just got my first scanner capable of scanning slides, and I'm wondering,
>>what resolution should I use for scanning slides so as to neither lose
>>data nor waste memory. Any thoughts? Thanks for any replies.
>
>
> Depends on what you want to do with the scanned images. If you are going
> to see them only on the PC screen or project with a standard projector, a
> resolution of 720 or 900 (allowing for some cropping during processing)
> will be adequate. No much benefit for any higher resolution (i.e.,
> increasing the pixel count) as the viewing software would reduce the pixel
> count to fit the screen. Some slides you may like to scan at a higher
> resolution if you wish to crop out a large section of the image.
>
> For printing, higher the better.
>
Also, if you are not going to be doing any editing, saving the files as
JPEG is probably okay. Better to use high res and JPEG than low res and
non-lossy file format.
Anonymous
February 24, 2005 1:13:09 PM

Archived from groups: rec.photo.digital (More info?)

Thanks for all the informative and helpful replies!
Anonymous
February 24, 2005 1:13:21 PM

Archived from groups: rec.photo.digital (More info?)

Don Stauffer in Minneapolis wrote:
> Gautam Majumdar wrote:
>
>> On Wed, 23 Feb 2005 21:48:59 +0000, Anthony Buckland wrote:
>>
>>
>>> Just got my first scanner capable of scanning slides, and I'm
>>> wondering, what resolution should I use for scanning slides so as
>>> to neither lose data nor waste memory. Any thoughts? Thanks for any
>>> replies.
>>
>>
>> Depends on what you want to do with the scanned images. If you are
>> going to see them only on the PC screen or project with a standard
>> projector, a resolution of 720 or 900 (allowing for some cropping
>> during processing) will be adequate. No much benefit for any higher
>> resolution (i.e., increasing the pixel count) as the viewing
>> software would reduce the pixel count to fit the screen. Some slides
>> you may like to scan at a higher resolution if you wish to crop out
>> a large section of the image. For printing, higher the better.
>>
> Also, if you are not going to be doing any editing, saving the files
> as JPEG is probably okay. Better to use high res and JPEG than low
> res and non-lossy file format.

And, two other considerations:

Storage Is Cheap. If the slides are at all valuable to you, it is worth
preserving even the enlarged grain;

You're more likely to be prepared for Advanced Technology as it evolves,
if you have bigger images (no telling when _that_ software will emerge;
I mean the one that looks at your Big Slide File and generates a
life-size hologram of your beloved pet naked mole rat).


--
Frank ess

Forecasting is difficult. Particularly about the Future.
-Deepak Gupta
Anonymous
February 24, 2005 7:38:22 PM

Archived from groups: rec.photo.digital (More info?)

Anthony Buckland wrote:

> Just got my first scanner capable of scanning slides, and I'm
> wondering, what resolution should I use for scanning slides
> so as to neither lose data nor waste memory. Any thoughts?
> Thanks for any replies.

Are you using a flatbed or dedicated film scanner?

I've got a 4K dpi film scanner and generaly scan everything at maximum
resolution and maximum color depth. I then open the scan in an image
editor and give it a look at 100% or 200% real size. If the image is
soft (SLow shutter without tripod, slightly out of focus, subject moved,
photographer was drunk, etc.) I'll resample it to a lower resolution.
I'll then do any neccessary color/brightness corrections by comparing
the image to the slide as it sits on a lightbox. Next, reduce the bit
depth to 24bit. Save as compressed TIFF and call it done.

IMO, 2000 dpi will be enough for most casual photographs. Even this is
too much for some P/S cameras, particularly when using faster print
films. Saving at usually 4000dpi makes sense only for slow slide films
that have been shot with a good lens.

If using a flatbed, forget alleged output DPI and scan at 2000 dpi or
less. While the scanner mfg. may brag about 4000+ dpi output, the
optics are seldom better than 1500~2000. Find a good sharp negative and
try scanning at increasing resolution. You'll reach a point where extra
dpi does not yield any gain in resolution or detail. Stop there.


-Greg
Anonymous
February 25, 2005 4:31:28 PM

Archived from groups: rec.photo.digital (More info?)

Hi,

How about quality with the new Epson 4990 flatbed (4800 dpi) and
costing ~$450-500?

Best,

Conrad


--
Conrad
Anonymous
February 26, 2005 1:32:04 PM

Archived from groups: rec.photo.digital (More info?)

Greg Campbell wrote:

> Anthony Buckland wrote:
>
>> Just got my first scanner capable of scanning slides, and I'm
>> wondering, what resolution should I use for scanning slides
>> so as to neither lose data nor waste memory. Any thoughts?
>> Thanks for any replies.
>
>
> Are you using a flatbed or dedicated film scanner?
>
> I've got a 4K dpi film scanner and generaly scan everything at maximum
> resolution and maximum color depth. I then open the scan in an image
> editor and give it a look at 100% or 200% real size. If the image is
> soft (SLow shutter without tripod, slightly out of focus, subject
> moved, photographer was drunk, etc.) I'll resample it to a lower
> resolution. I'll then do any neccessary color/brightness corrections
> by comparing the image to the slide as it sits on a lightbox. Next,
> reduce the bit depth to 24bit. Save as compressed TIFF and call it done.
>
> IMO, 2000 dpi will be enough for most casual photographs. Even this
> is too much for some P/S cameras, particularly when using faster print
> films. Saving at usually 4000dpi makes sense only for slow slide
> films that have been shot with a good lens.
>
> If using a flatbed, forget alleged output DPI and scan at 2000 dpi or
> less. While the scanner mfg. may brag about 4000+ dpi output, the
> optics are seldom better than 1500~2000. Find a good sharp negative
> and try scanning at increasing resolution. You'll reach a point where
> extra dpi does not yield any gain in resolution or detail. Stop there.
>
>
> -Greg

Thanks. I've now tried a few resolutions, and think I'll need to settle
on about 600dpi. At 2400
on my (5-year old Win98SE, 256 MBy, 1 GHz) machine, delivering the scan
to a file takes a
fair while, but _opening_ the file for editing, etc., takes forever and
practically flattens the
machine :( 
!