Re: Very slow colour scanning with Trust Imagery 1200SP (= Mustek MSF-06000SP)

Robert Brink (linux4me@dds.nl)
Thu, 31 Dec 1998 19:35:35 +0100

On Thu, 31 Dec 1998, I wrote:

>driver), I used an Adaptec AVA1505 (ISA SCSI host adapter) instead. Now the
>Windows TWAIN driver doesn't recognize the scanner anymore, but GIMP is a good
>alternative for commercial Windows programs, so that is not a big deal.

After a whole night of goofing around with my Linux system (think it was past
5AM when I went to sleep :-)) I finally got that #$(@$@! NCR53c400a card to
work with Linux, so I still can choose between Linux and Windows for scanning
images. The difference in image quality with flat gamma settings is not
noticable.

> 1. When scanning a colour image, the scanning head moves forward and back all
> the time, although I had not enabled "Force backtracking". All together
> scanning a simple phothograph with 200 dpi takes over 5 minutes, while with
> TWAIN this was a matter of seconds. I enlarged the buffer size in sg.h to
> 128kb and recompiled the kernel, but that didn't seem to have effect.

A bit of improvement here, but still the head moves 2 steps ahead and then 1
step back. Perhaps I should experiment with some setting???

<snip>
>3. CPU load is almost 100%, during scan you can't even move the mouse
>pointer!!!

I don't know what happened, but with that rotten NCR card without IRQ the
system load dropped to a mere 2% and during scan I could do whatever I like.
Anyway, this problem has been solved :-)))

>4. Gamma correction doesn't work fine, it causes the picture to look
>over-exposed very quickly (with white turning into blue). There may be a
>possibillity I have overlooked, as I don't know whether the scanner has
>built-in NVRAM which keeps downloadable software settings in memory. That would
>definitely impair scanning quality.

This one, and the fact that colour scanning still is extremely slow compared to
Windows-TWAIN, still bugs me. I tried to dive into the C source (mustek.c) but
can't seem to find where I can experiment with values to speed up things.

Enough for this year, I'm off to a party now :-)

Robert Brink
linux4me@dds.nl

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