Best scan size for 8x10 prints?

Hello,

Is there a general resolution/bit depth guideline to go by for highest
quality
8x10 prints?

I thought I would be real smart and test my new scanner (Nikon LS-8000) and
choose the absolute maximum size & bit depth for my first roll of 6x7 film
and save them as "tiff" files; well needless to say, they turned out pretty
big (356 megs ea. :-), which got me to thinking, I'm never going to print
anything larger than 8.5" x 11" (unless I replace my current printer) so
what should I be scanning them at to ensure the best possible quality,
without being totally absurd (356 meg files)? Any suggestions?

Thanks!

Ray

On Thu, 19 Feb 2004 20:19:07 -0800, "Lunaray"
wrote:

Hello,

Is there a general resolution/bit depth guideline to go by for highest
quality
8x10 prints?

I thought I would be real smart and test my new scanner (Nikon LS-8000) and
choose the absolute maximum size & bit depth for my first roll of 6x7 film
and save them as "tiff" files; well needless to say, they turned out pretty
big (356 megs ea. :-), which got me to thinking, I'm never going to print
anything larger than 8.5" x 11" (unless I replace my current printer) so
what should I be scanning them at to ensure the best possible quality,
without being totally absurd (356 meg files)? Any suggestions?


You certainly don't need the full resolution of
the LS-8000 to print 8x10" prints. Heck, I made
some pretty decent 8x10" prints with 18 Mbyte
files from my first film scanner, way back when.

On the other hand, are you absolutely, 100
percent sure you'll never print anything larger
than that, ever?

Scanning is a fairly laborious endeavor and
I for one don't enjoy doing it for its own sake.

A high res scan can be downsampled, but a
low res scan can never be upsampled to
yield the original detail from the film.

By my calculations a scan of 6x7 cm can't
be much larger than 300 Mbytes @ 4000 dpi,
and that's assuming the full frame area with
no cropping at all.


rafe b.
http://www.terrapinphoto.com

Thanks again for your help! Actually, my files are even bigger than I said,
I double checked and they're 565 megs each! I chose the highest bit-rate
available too, which I think was 14 bits per channel, though when I look at
the mode properties in Photoshop, "16 bits per channel" is checked, maybe
that's why they're so much bigger than the "300 meg" you quoted, ya think?

Ray
----------------------------------------------------------------------------
---------------
"Raphael Bustin" wrote in message
...
On Thu, 19 Feb 2004 20:19:07 -0800, "Lunaray"
wrote:

Hello,

Is there a general resolution/bit depth guideline to go by for highest
quality
8x10 prints?

I thought I would be real smart and test my new scanner (Nikon LS-8000)
and
choose the absolute maximum size & bit depth for my first roll of 6x7
film
and save them as "tiff" files; well needless to say, they turned out
pretty
big (356 megs ea. :-), which got me to thinking, I'm never going to print
anything larger than 8.5" x 11" (unless I replace my current printer) so
what should I be scanning them at to ensure the best possible quality,
without being totally absurd (356 meg files)? Any suggestions?


You certainly don't need the full resolution of
the LS-8000 to print 8x10" prints. Heck, I made
some pretty decent 8x10" prints with 18 Mbyte
files from my first film scanner, way back when.

On the other hand, are you absolutely, 100
percent sure you'll never print anything larger
than that, ever?

Scanning is a fairly laborious endeavor and
I for one don't enjoy doing it for its own sake.

A high res scan can be downsampled, but a
low res scan can never be upsampled to
yield the original detail from the film.

By my calculations a scan of 6x7 cm can't
be much larger than 300 Mbytes @ 4000 dpi,
and that's assuming the full frame area with
no cropping at all.


rafe b.
http://www.terrapinphoto.com

On Thu, 19 Feb 2004 23:03:26 -0800, "Lunaray"
wrote:

Thanks again for your help! Actually, my files are even bigger than I said,
I double checked and they're 565 megs each! I chose the highest bit-rate
available too, which I think was 14 bits per channel, though when I look at
the mode properties in Photoshop, "16 bits per channel" is checked, maybe
that's why they're so much bigger than the "300 meg" you quoted, ya think?


Yep, that's exactly what's happening. Scanning at 14 bits
doubles the file size.

Others have offered good advice on reducing your memory
requirements. Eg., do your high bit scans, followed by the
major color moves in Photoshop, followed finally by
conversion of your images to 8 bit mode, which will halve
their size.

Also, low-compression JPG gives a lot of bang for the buck.
Very minimal loss of image quality (I generally cannot
see it) and a very sizeable reduction in image size, usually
50-70%.


rafe b.
http://www.terrapinphoto.com

I understand (could be wrong, I'm not an expert) that Photoshop will show 16
bits in the mode window whenever the bits are more than 8 so the fact that
16 is checked doesn't necessarily mean it's really 16 bits, only that it's
something more than 8.

"Raphael Bustin" wrote in message
...
On Thu, 19 Feb 2004 23:03:26 -0800, "Lunaray"
wrote:

Thanks again for your help! Actually, my files are even bigger than I
said,
I double checked and they're 565 megs each! I chose the highest bit-rate
available too, which I think was 14 bits per channel, though when I look
at
the mode properties in Photoshop, "16 bits per channel" is checked, maybe
that's why they're so much bigger than the "300 meg" you quoted, ya
think?


Yep, that's exactly what's happening. Scanning at 14 bits
doubles the file size.

Others have offered good advice on reducing your memory
requirements. Eg., do your high bit scans, followed by the
major color moves in Photoshop, followed finally by
conversion of your images to 8 bit mode, which will halve
their size.

Also, low-compression JPG gives a lot of bang for the buck.
Very minimal loss of image quality (I generally cannot
see it) and a very sizeable reduction in image size, usually
50-70%.


rafe b.
http://www.terrapinphoto.com

Presuming 8"x10" inkjet color print which has at best 360'dpi' and 6x7cm
color negative - you want to scan at 16-bit with a sample of 1300-1400spi
('dpi') - that creates images of 3600x2880 pixels. You should get
uncompressed files of about 60mb per frame.

In article ,
"Reciprocity Failure" wrote:

I understand (could be wrong, I'm not an expert) that Photoshop will show 16
bits in the mode window whenever the bits are more than 8 so the fact that
16 is checked doesn't necessarily mean it's really 16 bits, only that it's
something more than 8.

I rather doubt Photoshop is operating on 14-bit units. It seems more
likely that use conventional word boundaries, so 16-bit it is.

"Lourens Smak" wrote in message
...
In article ,
Raphael Bustin wrote:

Also, low-compression JPG gives a lot of bang for the buck.
Very minimal loss of image quality (I generally cannot
see it) and a very sizeable reduction in image size, usually
50-70%.

JPG compression was designed especially to delete just the information
you wouldn't see anyway. That's why it works so well.

Actually, compression doesn't "delete" any information at all. It
_transforms_ the representation from a position/amplitude representation to
a frequence/amplitude representation.

This works because photographic images are not random data: you have areas
of smoothly changing color/brightness, and that sort of area can be recorded
perfectly accurately in a very small number of bits.

BUT (=big "but") you should only use jpg with the final product!
Changing the color, sharpening, etc. of a JPG could all bring out bad
jpg-effects quite quickly... certain manipulations can suddenly make the
compression very visible. (=banding, artefacts, etc)

If you use jpeg at settings such that the compression ratio is under 1:10,
there aren't any artifacts. You may lose a tad of contrast in the highest
contrast high-frequency detail, but scans don't have much of that, other
than noise.

David J. Littleboy
Tokyo, Japan

On Sat, 21 Feb 2004 09:54:51 +0900, "David J. Littleboy"
wrote:


"Lourens Smak" wrote in message
...
In article ,
Raphael Bustin wrote:

Also, low-compression JPG gives a lot of bang for the buck.
Very minimal loss of image quality (I generally cannot
see it) and a very sizeable reduction in image size, usually
50-70%.

JPG compression was designed especially to delete just the information
you wouldn't see anyway. That's why it works so well.

Actually, compression doesn't "delete" any information at all. It
_transforms_ the representation from a position/amplitude representation to
a frequence/amplitude representation.


As I understand it, JPG involves transformation from
RGB to YCbCr, and then decimation of the Cb and Cr
data, typically 2:1 in each axis (4:1 in total data, for these
two channels.)

The remaining compression in JPG comes from the DCT
transform, and the ability to control the bit depth of the
resulting DCT output. Eg., low compression might use
8 bits, high compression might use just 4 bits -- etc.

The DCT terms themselves are Huffman encoded, so
that part is lossless.


This works because photographic images are not random data: you have areas
of smoothly changing color/brightness, and that sort of area can be recorded
perfectly accurately in a very small number of bits.

BUT (=big "but") you should only use jpg with the final product!
Changing the color, sharpening, etc. of a JPG could all bring out bad
jpg-effects quite quickly... certain manipulations can suddenly make the
compression very visible. (=banding, artefacts, etc)

If you use jpeg at settings such that the compression ratio is under 1:10,
there aren't any artifacts. You may lose a tad of contrast in the highest
contrast high-frequency detail, but scans don't have much of that, other
than noise.

There are still some artifacts due to the fact that the DCT operates
on cells of 8x8 pixels. I've seen these cells even when using the
very lowest-compression (highest-quality) JPG settings in Photoshop.


rafe b.
http://www.terrapinphoto.com

On Fri, 20 Feb 2004 13:23:32 GMT, "Reciprocity Failure"
wrote:

I understand (could be wrong, I'm not an expert) that Photoshop will show 16
bits in the mode window whenever the bits are more than 8 so the fact that
16 is checked doesn't necessarily mean it's really 16 bits, only that it's
something more than 8.


Yep, anything above 8 bits requires a 16-bit field,
since tradtional computer architectures support
data sizes of either 8, 16, 32, or 64 bits. (Floating
point is another story.)


rafe b.
http://www.terrapinphoto.com