How to improve scanning speed (b/w, 600 dpi)?

[Daniel M.]

Hello everybody,

I scan a lot of b/w documents, 600 dpi, on my Epson Perfection 2400.
A full scan takes about 40 seconds, and a scanning head often stops during
a pass for a couple of seconds, as though there is some processing going on
(all in all, there are 7 stops for a single pass). When I scan b/w documents
using 300 dpi resolution, no stops are made (and a scan takes about 15 seconds).

The question is whether it is somehow possible to improve scanning speed - 40
seconds for a single is too slow if you have to scan a lot of documents .
I connect scanner to USB 1.1 slot, so I though that maybe upgrading to USB 2
could improve scanning speed - maybe it is going to eliminate those stops in
the middle, but I am not sure that this is the problem - after all, a 600 dpi
scan, even when made in a grayscale, (8 bits) takes up only 5 Mb, and b/w scan
much less than that (~100Kb), while USB 1.1's transfer speed is 12Mbps, which
seems more than enough, and I have no other devices connected to USB bus (BTW,
I have Athlon 1.33 (750 Mb RAM) - it looks like scanning also takes a lot of
CPU cycles).

Or maybe there are also some other ways to improve speed?

Daniel.

 

[Winfried]

Hello everybody,

I scan a lot of b/w documents, 600 dpi, on my Epson Perfection 2400.
A full scan takes about 40 seconds, and a scanning head often stops during
a pass for a couple of seconds, as though there is some processing going on
(all in all, there are 7 stops for a single pass). When I scan b/w documents
using 300 dpi resolution, no stops are made (and a scan takes about 15 seconds).

The question is whether it is somehow possible to improve scanning speed - 40
seconds for a single is too slow if you have to scan a lot of documents .
I connect scanner to USB 1.1 slot, so I though that maybe upgrading to USB 2
could improve scanning speed - maybe it is going to eliminate those stops in
the middle, but I am not sure that this is the problem - after all, a 600 dpi
scan, even when made in a grayscale, (8 bits) takes up only 5 Mb, and b/w scan
much less than that (~100Kb), while USB 1.1's transfer speed is 12Mbps, which
seems more than enough, and I have no other devices connected to USB bus (BTW,
I have Athlon 1.33 (750 Mb RAM) - it looks like scanning also takes a lot of
CPU cycles).

Or maybe there are also some other ways to improve speed?

Daniel.

I just looked at the technical specications. It says, it takes 3.3
millisecond/row for b/w and color.
Let's do some mathematics. The flatbed is about 12 inch, at 600dpi this
results in 12*600 rows = 7200 rows. The best you can get is 7200 * 3.3
milliseconds = 24 seconds. Therefor a usb2-interface might bring some
improvement. But 24 seconds is the limit.
I just crosschecked with my Epson 2450 (slower than the 2400) with this
result: 7200 * 3.8 milliseconds = 27.5 seconds, exactly plus/minus 1
second what I can measure.

Winfried

 

[Terry]

2400.

I don't understand why you are scanning b/w documents a 600 dpi. Thats
way too much resolution for a b/w document. I would suggest 150 dpi at
1 bit or 8 bit at the most for b/w documents and 300 dpi, 24 bit for
color phothgraphs. Most photographs don't have much more information
than a 300 dpi scan give. The reason for scanning at a larger dpi
setting is to enlarge your image. It allows you to print larger than
life without losing quality.

There is no benefit in scanning documents at 600 dpi, except it slows
down your scanner and makes for a large file.

 

[Daniel M.]

2400.

I don't understand why you are scanning b/w documents a 600 dpi. Thats
way too much resolution for a b/w document. I would suggest 150 dpi at
1 bit or 8 bit at the most for b/w documents and 300 dpi, 24 bit for
color phothgraphs. Most photographs don't have much more information
than a 300 dpi scan give. The reason for scanning at a larger dpi
setting is to enlarge your image. It allows you to print larger than
life without losing quality.

There is no benefit in scanning documents at 600 dpi, except it slows
down your scanner and makes for a large file.

Usually I scan documents with a lot of mathematical formulae, which
usually contain many small letters, and often, especially if paper's
quality is not great, 300 is not enough - you cannot discern between
small 'i' and 'j', for example, which is very important.

Daniel.

 

[Terry]

I have a Epson 4870 Photo scanner , its connected by firewire to my
computer.
in the 8 bit 300 dpi mode it takes 12 seconds to do a full scan of the
entire bed and makes a 8.5 Meg file.

If i change the settings to 600 dpi it takes 24 seconds to do a full
scan of the entire bed and makes a 34 meg file. (I don't know where
you get the 5 meg file for 600 dpi, you must not be scanning the whole
bed. If you are not scanning the whole bed then your scans should be
faster.)

Since USB 2 is a little faster than Firewire It should take about the
same time to do a 600 dpi file just like the figure Winfred came up
with, Isn't math wonderful.

You might want to try a USB 2.0 interface, it may save you a lot of
time in the long run.

 

[John]

2400.

I don't understand why you are scanning b/w documents a 600 dpi. Thats
way too much resolution for a b/w document. I would suggest 150 dpi at
1 bit or 8 bit at the most for b/w documents and 300 dpi, 24 bit for
color phothgraphs. Most photographs don't have much more information
than a 300 dpi scan give. The reason for scanning at a larger dpi
setting is to enlarge your image. It allows you to print larger than
life without losing quality.

There is no benefit in scanning documents at 600 dpi, except it slows
down your scanner and makes for a large file.

That's quite wrong. Line art and text scanned as 1-bit bitmaps need to be
scanned at as high a resolution as possible in order to resolve fine lines,
serifs, etc. In addition, the printer dpi should be equal to or a multiple
of the resolution . For example, for printing to a 600dpi laser printer, 600
ppi is ideal, 300ppi would be noticeably grittier. 150ppi would be useless.
I sometimes scan at 1200ppi for very intricate black and white graphics and
text, although only when I am in my pickier moods and when I feel like a
coffee

Obviously, 1-bit bitmaps file sizes are smaller than corresponding greyscale
and colour files, so the high resolution should not pose that much of a
problem. However, scan times will be longer.