[sane-devel] mustek backend - is everything ok?

[Henning Meier-Geinitz]

Hi,

On Wed, Sep 19, 2001 at 09:26:50AM +0200, Christoph Kukulies wrote:
> E.g. I scanned an area like:
> 
> scanimage --resolution 300 -l 50 -t 50 -x 100 -y 100 >l1 2>l2
> 
> and got 75 KB/s

68 KB/s here.

> Doing the same, but x=200:
> 
> scanimage --resolution 300 -l 50 -t 50 -x 200 -y 100 >l1 2>l2
> 
> I get 126 KB/s.

108 KB/s here. So your values are quite good.

> This may be normal because a whole line of a scan is probably
> more effective than a portion of it,

The scanning time is limited by the rate of data the hardware inside
the scanner can handle and usually not by the tranfer from the scanner
to the computer. The motor speed is dependant on the resolution and
the mode (colour, gray, ...) and nothing else. So it's fastest
(seconds/scan) at gray mode, low resolution, big width.

> although I'm wondering whether
> I could tune the parameters a bit to get even better
> results. Also, what are good scan rates with these Mustek 12000SP
> scanners?

At least in this mode, you can't optimize this further. The only thing
you can do, is to increase the SCSI buffer size, but this will only
help, when the scan slider stops during the scan.

All the low level computation is done in the scanner. The backend only
tells the scanner the mode, the resolution and the coordinates. Things
like motor speed, real optical resolution and backtracking is done by
the scanner's internal firmware.

Some examples from my Scanner (using an Adaptec 2940, full page):

Gray, 75 DPI: 27 seconds, 23 kB/s
Gray, 200 DPI: 45 seconds, 102 kB/s
Gray, 300 DPI: 45 seconds, 229 kB/s
Gray, 600 DPI: 84 seconds, 492 kB/s
Gray; 1200 DPI: 166 seconds, 997 kB/s
Color, 75 DPI: 53 seconds, 36 kB/s
Color, 200 DPI: 90 seconds, 153 kB/s
Color, 300 DPI: 92 seconds, 338 kB/s
Color, 600 DPI: 165 seconds, 754 kB/s
Color; 1200 DPI: 321 seconds, 1550 kB/s

> Henning, does this log reflect that I have the latest mustek backend?

Yes.

Here are some values from a different scanner for comparison:
Mustek ScanExpress 12000SP (SCSI, A4 size, full page):

Gray, 300 DPI: 35 seconds, 247 kB/s
Gray, 600 DPI: 64 seconds, 541 kB/s
Gray, 1200 DPI: 119 seconds, 582 kB/s
Color, 300 DPI: 48 seconds, 543 kB/s
Color, 600 DPI: 94 seconds, 1109 kB/s
Color, 1200 DPI: 199 seconds, 1048 kB/s 

Bye,
  Henning