Scanner Resolution for Color Photo Print

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Andrew

I just wonder what resolution you folks here set when you use flatbed to
scan color photo print. Would 4800 dpi get any better than 1200 dpi?
Or 4800 dpi just a waste of time? I just do not have all the time and
storage space to store all photos in 4800 dpi...
 
I just wonder what resolution you folks here set when you use flatbed to
scan color photo print. Would 4800 dpi get any better than 1200 dpi?
Click to expand...

Probably not. In fact, even 1200 is almost certainly overkill. I'd use
300 dpi myself, if the prints are from a typical photofinisher. If
they're from a custom lab that does really good work, it *might* be worth
going to 600 dpi.
 
I just wonder what resolution you folks here set when you use flatbed to
scan color photo print. Would 4800 dpi get any better than 1200 dpi?
Or 4800 dpi just a waste of time? I just do not have all the time and
storage space to store all photos in 4800 dpi...
Click to expand...


It depends on the goal. If you are going to print a copy to be the same
size of the original print, I'd scan it at 300 dpi.

If you are not going to print it, but will only view it on the video
screen, then about 150 dpi probably gives you a more usable image size
(100 to 200 dpi range for scanning a 4x6 inch print).
 
This makes sense, but when you'll need the 4800 dpi resolution? Or that is
for other things, like text or others? Or to rephrase, what do they make the
4800 dpi for ?
 
Andrew <[email protected]> said:
I just wonder what resolution you folks here set when you use flatbed to
scan color photo print. Would 4800 dpi get any better than 1200 dpi?
Or 4800 dpi just a waste of time? I just do not have all the time and
storage space to store all photos in 4800 dpi...
Click to expand...
Neither does your computer!! ;-)

Seriously, most systems would fall over if you try to scan a photo
typical sized photo at 4800ppi.

IIRC the largest possible TIFF file is 4Gb, and the uncompressed TIFF
format is often used as an intermediary file format even if the final
storage is as a jpeg or something else. In addition, the largest file
that FAT-16 or FAT-32 can cope with is 4Gb, so unless you are using NTFS
forget about it. At 4800ppi and 48-bit colour, you would exceed these
limits with only a 7"x5" image!

Since most scanner drivers transfer the image directly to memory by DMA,
you need enough real system memory to accept the image data. At 4800ppi
with 48-bit colour, 1Gb of RAM corresponds to an image area no greater
7.77 sq.in, or 15.5sq.in for 24-bit colour. This does not include any
allowance for the operating system or other software that needs to
occupy memory - so you can probably take at least 30% off those values
depending on your system and what else is installed.

So, even though marketing hype tells you that the scanner has 4800ppi,
even if you had something of significant area that could use this
capability - eg a hand painted relic - your system most likely couldn't
cope and pretty soon you would reach the limit of current image
standards in any case.

4800ppi is strictly for small area scans, and no photographic print has
enough intrinsic detail to require that resolution. Not by a long way.
For colour photos, 300ppi is more than adequate, some B&W images may
need 600ppi and contact prints might require 800-1200ppi depending on
the source. After that, there are too many losses involved in the
production of photographic prints to justify additional resolution.
4800ppi is useful for scanning first generation photographic images on
film, either as negative or as slides.
 
The reason for my asking again is that I see a lot of discussions on
Epson 4870 which is a high resolution flatbed. I know flatbed is not
good for films. Just curious.

I just picked up a 1200 dpi flatbed and returned my 4800 dpi one
and save some $$. I plan to get a film scanner when I'm done with my
color prints.

Right now I scan color print at 1200 dpi and save them as TIFF.
I know this may be overkill, but I have a good PC and about 600GB HDs
and the DVD-RW. And I do not want to scan them again.

Definitely I'll need more RAM if I want to do 4800 dpi :-) Tried it with
one or two color prints and could not get anything done....
 
This makes sense, but when you'll need the 4800 dpi resolution? Or that is
for other things, like text or others? Or to rephrase, what do they make the
4800 dpi for ?
Click to expand...


Resolution is used for enlargement. So you might use 4800 dpi for scanning
and enlarging small things. Printing an 11x17 inch print from tiny 35 mm
film requires substantial enlargement. Printing a 6x4 inch print from a 6x4
inch print does not.

The ratio of (scanning resolution / printing resolution) is the enlargement
factor.

For example,

Scan at 600 dpi, print at 300 dpi, for 600/300 = 2X size (double size or 200%
size)
Scan at 300 dpi, print at 300 dpi, for 300/300 = 1X size (original size or
100% size)
Scan at 150 dpi, print at 300 dpi, for 150/300 = 1/2X size (half size or 50%
size)

Or scan film at 2700 dpi, print at 300 dpi, for 2700/300 = 9X size. 9X is
about 8x12 inches (about A4 size) from full frame 35 mm (about 0.9 x 1.4
inches). The ratio of (scanning resolution / printing resolution) is the
enlargement factor.

See the site below for basics.
 
The reason for my asking again is that I see a lot of discussions on
Epson 4870 which is a high resolution flatbed. I know flatbed is not
good for films. Just curious.
Click to expand...
35 mm film is not the only film that is scanned. Some photographers
still use large format cameras... and for those, the 4800 ppi flatbed
scanners do a reasonable job at moderate cost.
I just picked up a 1200 dpi flatbed and returned my 4800 dpi one
and save some $$. I plan to get a film scanner when I'm done with my
color prints.

Right now I scan color print at 1200 dpi and save them as TIFF.
I know this may be overkill, but I have a good PC and about 600GB HDs
and the DVD-RW. And I do not want to scan them again.

Definitely I'll need more RAM if I want to do 4800 dpi :-) Tried it with
one or two color prints and could not get anything done....
Click to expand...

Charlie Hoffpauir
http://freepages.genealogy.rootsweb.com/~charlieh/
 
Andrew said:
I just wonder what resolution you folks here set when you use flatbed to
scan color photo print. Would 4800 dpi get any better than 1200 dpi?
Or 4800 dpi just a waste of time? I just do not have all the time and
storage space to store all photos in 4800 dpi...
Click to expand...

If you're looking at anything other than an exhibition print by a
master printer, on glossy or *very* smooth matte paper, there's no
point in scanning at any resolution about 300dpi.
 
Andrew said:
This makes sense, but when you'll need the 4800 dpi resolution? Or
that is for other things, like text or others? Or to rephrase, what
do they make the 4800 dpi for ?
Click to expand...

Checklist shoppers who don't know anything about scanners, mostly.
Although scanning real-world objects, as opposed to photo prints, can
get you interesting things at higher resolutions.

Or, if your scanner can be equipped with a transparency adapter for
scanning slides and negatives, then the higher resolutions are useful
for them.
 
Andrew said:
I just wonder what resolution you folks here set when you use flatbed to scan
color photo print. Would 4800 dpi get any better than 1200 dpi? Or 4800 dpi
just a waste of time? I just do not have all the time and storage space to
store all photos in 4800 dpi...
Click to expand...

Usually 300 dpi is pretty good. On a very crisp and clean print, 600 dpi is
about as much real resolution that you can suck out of it.
 
Andrew said:
This makes sense, but when you'll need the 4800 dpi resolution? Or that is
for other things, like text or others? Or to rephrase, what do they make the
4800 dpi for ?
Click to expand...

For line art, fine text, etc. the higher res can be useful, though not often.
The hi resolutions offered by the vendors is mainly a cheaply achieved
performance number that is perfectly useless for 99% of scanning needs.

Those flatbed scanners that offer transpareny scanning as well can be used to
scan slides, negatives and transparencies, though they do not do this as well as
a dedicated film scanner... which DO extract useful information at ca. 5000 dpi
from the film.

Cheers,
Alan
 
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