HP ScanJet IIc ADF report

Nick Lamb (njl98r@ecs.soton.ac.uk)
Sun, 14 Mar 1999 04:03:10 +0000 (GMT)

Well, I've finally got access to an HP scanner, so that my ramblings on
this list are supported by more than the PNM backend and a desire to learn.

The scanner is an ancient HP ScanJet IIc with an ADF, and it is connected
to a Pentium 90 with a DPT SCSI card of the same vintage as the scanner.
The Pentium 90 usually runs Windows 95, but I've installed a Linux 2.2.2
kernel with 64Kb SG_BIG_BUF and I'm talking to it mostly via saned & net.

Discoveries so far

(1) Although the frontends report a resolution up to 1600 dpi the scanner
really only offers up to 800 dpi real (optical?) resolution.

(2) 800 dpi is a lot of bandwidth. The scanner backtracks in all modes
but B&W if the resolution and scan width exceed certain values.

(3) Even when backtracking, Linux + SANE is faster than Win95. A decent
high resolution colour scan takes half as long in Linux as Win95.

(4) The network doesn't slow down scanning (perhaps it even speeds it up
since the hard disk is on the same SCSI controller as the scanner)

(5) Playing with the load next/ eject etc. stuff in xscanimage causes it
to crash. The remote saned seems fine, so presumably this is a network
backend or xscanimage bug. I had trouble tracking this down further.

I also found (and reported) an Xsane memory allocation bug.

Nick.

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