[sane-devel] Reflecta ProScan / Crystalscan 7200 PIE film scanner update

[Vleeshouwers, J.M.]

Hi Michael,

I tested your modified Pie backend this weekend. I had to change one line to get it working. My scanner takes about 10 seconds to get ready after it decides to collect shading data after all. So in pie_usb_calibrate() I changed line 3307 to:
status = pie_usb_wait_scanner (scanner, 30);
(30 to be very safe) I also changed the polling frequency of pie_usb_wait_scanner() from 16 times per second to just 1 time per second. The windows driver only polls every 1.5 second. I did not check if this was essential, though.

With this change scanimage -L, -A and -T all work. And although I did not expect it, /tmp contains the scanned and cleaned image and a couple of auxiliary files. I'm impressed, the scratch/dust removal works very well!.

While you are thinking about the proposal to create a separate backend for the Reflecta scanners, I got two more detailed questions for you:
1. When doing shading correction, your routine only corrects 2-byte values >4096 and 1-byte values >16. It looks like an efficiency issue, right? How much faster is it?
2. I did not yet study the dust/scratch removal functions. What seems critical me is how much memory they use, knowing that the Windows driver gets into memory trouble at high resolutions. Do these functions allow processing the data stream from scanner to frontend with limited buffering in between?

Yours,

Jan

________________________________________
From: Klaus Kaempf [kkaempf at suse.de]
Sent: Monday, September 10, 2012 3:09 PM
To: Michael Rickmann
Cc: sane-devel at lists.alioth.debian.org; Vleeshouwers, J.M.
Subject: Re: [sane-devel] Reflecta ProScan / Crystalscan 7200 PIE film scanner update

Michael,

thanks a lot for posting your changes !

* Michael Rickmann <mrickma at gwdg.de> [Aug 21. 2012 22:28]:
>
> Now my questions:
> Would code like the one in the patch be acceptable in SANE?
> Would a separate backend be preferable to patching pie?

Looking at the amount of changes required to properly support USB PIE
devices and the high risk to break SCSI PIE devices, I'm meanwhile all
for a separate backend.

Regards,

Klaus
--
SUSE LINUX Products GmbH, GF: Jeff Hawn, Jennifer Guild, Felix Imendörffer, HRB 16746 (AG Nürnberg)
Maxfeldstraße 5, 90409 Nürnberg, Germany