Scanning 4x5 on epson 4870 at 16-bits/channel

[Roger N. Clark (change username to rnclark)]

Hi
I bought an epson 4870 scanner today for the purpose
of scanning 4x5 fuji velvia. I have done many tests
and I am very satisfied with the results, scanning at
4800 ppi and 48-bits, then downsizing to 3200 ppi but
keeping the 16 bits for processing. I can pull a lot
of nice detail out of the shadows if I want with the 16-bit.
Results are similar to drum scans I've done.

So now I'm ready to scan a full size 4x5 sheet.
4.67 x 3.70 inches at 4800 ppi, 48-bit:
I get the error
"Selected area is too large for this resolution"

Same at 3200, 48-bit. Only when I go down to 3200 ppi and 24-bit
can I scan a full size 4x5.

I'm running a 1.8 GHz win xp box with 1 GByte of ram.

I get the same results if I run as a plugin to photoshop cs or
as epson scan standalone.

Has anyone had/solved this problem? If you successfully scan
full size 4x5 at 4800 ppi and 48-bit, what kind of setup do you have?

Thanks,
Roger Clark

 

[Raphael Bustin]

Has anyone had/solved this problem? If you successfully scan
full size 4x5 at 4800 ppi and 48-bit, what kind of setup do you have?

Have you considered the memory and bandwidth
limitations of what you're attempting?

4800 dpi is 23 million pixels per square inch.
Times 20 square inches is 460 million pixels.

That's 1.38 gigabytes at 24 bit color, 2.76 Gb
at 48-bit. That 2.76 G image will take 5 minutes
to move off the scanner and onto your PC or
Mac at 9.2 Mbytes/s.

FWIW, I'm scanning 4x5 at 2500 dpi and
those 330 Mbyte files are killing me <G>.


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

 

[Mac McDougald]

Have you considered the memory and bandwidth
limitations of what you're attempting?

4800 dpi is 23 million pixels per square inch.
Times 20 square inches is 460 million pixels.

.... 2.76 Gb at 48-bit.

Which can't even be saved in most imaging programs.
Photoshop can't handle over 2GB PSD or TIFF.
The CS version can, but only in a proprietary file format, not PSD or
TIFF.

And no, saving as JPEG won't help at any compression rate either, as has
to open at full pixel dimensions/filesize in Photoshop, ala TIFF.


Mac

 

[Mac McDougald]

Which can't even be saved in most imaging programs.
Photoshop can't handle over 2GB PSD or TIFF.
The CS version can, but only in a proprietary file format, not PSD or
TIFF.

And no, saving as JPEG won't help at any compression rate either, as has
to open at full pixel dimensions/filesize in Photoshop, ala TIFF.


Mac

Let me rephrase that slightly....what happens is, Photoshop will
generally be able to SAVE the >2GB image. It just won't re-open it

M

 

[Leonard Evens]

Hi
I bought an epson 4870 scanner today for the purpose
of scanning 4x5 fuji velvia. I have done many tests
and I am very satisfied with the results, scanning at
4800 ppi and 48-bits, then downsizing to 3200 ppi but
keeping the 16 bits for processing. I can pull a lot
of nice detail out of the shadows if I want with the 16-bit.
Results are similar to drum scans I've done.

So now I'm ready to scan a full size 4x5 sheet.
4.67 x 3.70 inches at 4800 ppi, 48-bit:
I get the error
"Selected area is too large for this resolution"

Same at 3200, 48-bit. Only when I go down to 3200 ppi and 24-bit
can I scan a full size 4x5.

I'm running a 1.8 GHz win xp box with 1 GByte of ram.

I get the same results if I run as a plugin to photoshop cs or
as epson scan standalone.

Has anyone had/solved this problem? If you successfully scan
full size 4x5 at 4800 ppi and 48-bit, what kind of setup do you have?

Thanks,
Roger Clark

This just came up in the photo.net digital darkroom forun. See
www.photo.net/bboard/q-and-a-fetch-msg?msg_id=008ICU

See Doug Fisher's response. It seems that it won't work at 4800 ppi if
you have digital ICE turned on. But it should work if you turn it off.
It seems to be a problem with the software. So it might work fine with
Vuescan.

By the way, I regularly scan 4 x 5 with and Epson 3200 at 16 bits per
channel using Vuescan.

 

[Steve]

So now I'm ready to scan a full size 4x5 sheet.
4.67 x 3.70 inches at 4800 ppi, 48-bit:
I get the error
"Selected area is too large for this resolution"

I'm not too suprised at this a scan of 4.67" X 3.7" at 4800 ppi and
16bits per channel results in a scan size of about 2.39 Gbytes!

You will need to scan at a lower resolution for this size of scan,
especially at 16 bits.

Steve.

 

[Chris Brown]

Which can't even be saved in most imaging programs.
Photoshop can't handle over 2GB PSD or TIFF.
The CS version can, but only in a proprietary file format, not PSD or
TIFF.

Does VueScan handle >2gig files?

 

[David J. Littleboy]

I'm not too suprised at this a scan of 4.67" X 3.7" at 4800 ppi and
16bits per channel results in a scan size of about 2.39 Gbytes!

You will need to scan at a lower resolution for this size of scan,
especially at 16 bits.

Or you can scan in sections that overlap, process each section identically,
and then stitch together in Photoshop after you've downsampled to a more
sensible resolution.

You should be able to downsample to 3000 dpi with no loss of information
(since someone here reported 30 lp/mm in one direction and 40 lp/mm in the
other, and 40 lp/mm is (assume 3 pixels per line pair) 40x3x25.4 = 3048).

IMHO, even 2700 dpi would be fine, but 3050 is safe.

4x5 at 3050 dpi = 180MP
4x5 at 2700 dpi = 146MP
3.7x4.7 at 2700 dpi = 127MP

You'll want 2GB of RAM to handle those files, but at least it's possible.

David J. Littleboy
Tokyo, Japan

 

[Ed Hamrick]

Does VueScan handle >2gig files?

I don't think so, but I've never tested this. It depends
on the inner workings of the TIFF library I'm using, and
I haven't tested this.

Regards,
Ed Hamrick

 

[Tim]

This is a programming restriction because the EPSON Scan transfers RGB
information in one go rather than individually (probably a Twain
requirement). There is normally a limitation of 74Kb of data per line
of scanned data that can be transferred (hardware limitation).

For example:

At 48bit colour 1 pixel = 6 bytes.

At 4800 dpi and 48 bit colour the maximum width of scan will be 2.6
inches.

Max scan width in bytes (74 x 1024)
----------------------------------- = Maximum width of scan
Scan resolution in bytes (dpi x 6)

75766 (74 x 1024)
----------------- = 2.6 inches
28800 (4800 x 6)

The 10,925 pixel limit is the same though this works out to a maximum
scan line of 64Kb for both 48 and 24 bit colour:

10925 at 48 bit colour = 65.550 bytes (64Kb)

21845 at 24 bit colour = 65.535 bytes (64Kb)

This is odd as I would have expected a maximum scan line of 12,627
pixels for 48 bit colour and 25,255 pixels in 24 bit colour. But it
may be that there is a limitation of 64Kb per scan line for the
Perfection 4870.

 

[jjs]

So now I'm ready to scan a full size 4x5 sheet.
4.67 x 3.70 inches at 4800 ppi, 48-bit:
I get the error
"Selected area is too large for this resolution"

Since I can't see the program code, I have to guess that the image size
will be larger than addressable memory (plus program size.)

Do you really need 4800spi/48-bit? You can't use it with any conventional
imaging software. You can't print it, either. I'd suggest you lower the
bit sample to something manageable. You will always have the transparency
in the future when/if digital catches up.

 

[Bart van der Wolf]

I don't think so, but I've never tested this. It depends
on the inner workings of the TIFF library I'm using, and
I haven't tested this.

Don't most operating systems impose a 2GB ceiling for a single file?

Bart

 

[Chris Brown]

I don't think so, but I've never tested this. It depends
on the inner workings of the TIFF library I'm using, and
I haven't tested this.

I supoose a more pertinent question is, is there are file format in common
use that can reliably support images which won't fit in the virtual
addressing space of typical 32 bit processors, other than the new Photoshop
format? After all, once you have all that data, it has to be stored somehow.

To the OP - I guess you might get some joy from scanning in two halves, and
then stitching back together in CS. Make sure you have stupid amounts of RAM
before trying this, though...

 

[Chris Brown]

Or you can scan in sections that overlap, process each section identically,
and then stitch together in Photoshop after you've downsampled to a more
sensible resolution.

If you have Photoshop CS, you won't need to downsample. Having a 64 bit
machine with lots of RAM (e.g. a G5 with 6 gigs) may be useful here, a 32
bit system with 2 gigs will get there eventually, but it'll be painful.

 

[jjs]

Don't most operating systems impose a 2GB ceiling for a single file?

No, thank goodness. However, for most of us the practical limit for a
single image is 4bg to 8gb. Photoshop CS, for example, has a feature to
handle very large images.

But a little arithmetic will show you that there are only rare
circumstances in which a photographer (raster image work) will need an
image that large, and even then it can be handled in mutiple file rather
then one huge one.

Just how large a raster image does one need for printing when printers
don't 'resolve' better than 360spi with shallow bit depth?

 

[Dances With Crows]

["Followup-To:" header set to comp.periphs.scanners.]

Don't most operating systems impose a 2GB ceiling for a single file?

No. Win9x, Linux kernels on x86 machines before 2.2.14 or so (or any
Linux distro using the ancient ReiserFS 3.5), and MacOS < X could have
problems with files larger than 2G. There's a 2G limit on file size if
you're using FAT32 with a normal (4K) block size, which may be an
incentive for you to move to a Real OS that uses a Real Filesystem.

I'd be surprised if the standard tifflib from SGI had problems with
files larger than 2G, but architecture and OS-specific weirdness could
throw monkey wrenches into the works. I've never seen a TIFF that large
in the wild, but most of the TIFFs I work with are 1-bit.

 

[jjs]

If you have Photoshop CS, you won't need to downsample. Having a 64 bit
machine with lots of RAM (e.g. a G5 with 6 gigs) may be useful here, a 32
bit system with 2 gigs will get there eventually, but it'll be painful.

First, I don't believe it's truely 64-bit yet. But regardless, CS can't
address more than 2gb of RAM, and in fact you will probably find it
addressing only 1.8gb. A significant performance factor in CS will be
found in using multiple spindles for work files. CS uses its own
proprietary paging scheme and will page regardless of the amount of RAM
but of course more is better because you can have other applications in
the remaining space.

We get along well enough with 4gb RAM and two spindles (G5, dual
processor). Well, we did until the machine smoked last week, but it's
under warantee.

 

[jjs]

I supoose a more pertinent question is, is there are file format in common
use that can reliably support images which won't fit in the virtual
addressing space of typical 32 bit processors, other than the new Photoshop
format? After all, once you have all that data, it has to be stored somehow.

TIFF up to 8gb, but for all practical purposes 4gb.

To the OP - I guess you might get some joy from scanning in two halves, and
then stitching back together in CS. Make sure you have stupid amounts of RAM
before trying this, though...

If the goal is a huge image, don't even worry about the RAM. RAM isn't the
limiting factor. Start the job and go to lunch. However, there are better
utilities than Photoshop for tiling.

 

[David J. Littleboy]

If you have Photoshop CS, you won't need to downsample. Having a 64 bit
machine with lots of RAM (e.g. a G5 with 6 gigs) may be useful here, a 32
bit system with 2 gigs will get there eventually, but it'll be painful.

But not downsampling is silly. The scanner simply isn't capturing 4800 dpi
of real data; it's a 30 lp/mm x 40 lp/mm resolution device, and at the
Nyquist frequency, that's 1500 dpi x 2000 dpi.

While using enough pixels that the max signal in the data is at 2/3 Nyquist
is more than adequate (3000 dpi), what I really think is that downsampling
to 2400 dpi is the right thing with that scanner, just as the 2450 captured
barely 1200 dpi worth of real information.

I'm quite sure that if you scanned the same frame (35mm or MF) with a Nikon
4000 dpi scanner and the 4870, and downsampled both to 2400 dpi, the Nikon
scan would look a lot better.

And 6GB of memory is still quite serious money.

Besides, 2400 dpi from 3.7x4.7 is a 30x38" print at 300 dpi, more than
enough for most purposes.

David J. Littleboy
Tokyo, Japan

 

[Chris Brown]

Don't most operating systems impose a 2GB ceiling for a single file?

OS X seems to cope:

Narcissus:~ cbrown$ ls -l foo
-rw-r--r-- 1 cbrown staff 5000000000 May 19 17:26 foo