[sane-devel] epsonds backend ADF size with ES-50

Ralph Little skelband at gmail.com
Wed Aug 31 17:34:55 BST 2022


On Tue, Aug 30, 2022 at 10:36 PM Sean Greenslade <sean at seangreenslade.com>

> Hi, all. I recently picked up an Epson ES-50 sheet-feed scanner. My
> intent is to use it for receipt scanning, so I tried it out with a
> ~700 mm long receipt and found that it would error out at around 450 mm
> into the scan. The manual claims the scanner is capable of a max of 72
> inch document length, so I started poking around in the epsonds backend
> code.  Something that jumped out at me was the eds_set_adf_area
> function. It seems that for this particular scanner, three ADF size
> values are reported: AREA, AMIN, and AMAX (in epsonds-cmd.c around line
> 445 on current git master). The eds_set_adf_area function is called with
> the values from AREA, which limits the document length to 14 inches. I'm
> assuming AREA is just meant to be a default value, but if anyone has any
> deeper insight into the meaning, I'd be interested to know.

Looking at that code, AMIN and AMAX are pretty much ignored.
What do you get for all of the AREA/AMIN/AMAX parameters?
Perhaps we can figure out what they mean and code up something a little

> The AMAX values reported seemed to match the manual's reported 72-inch
> maximum, so on a whim, I just moved the eds_set_adf_area call to the
> AMAX section. After recompiling, I was able to scan my long receipt no
> problem.
> Now I'm wondering if there is any downside to using the max ADF size? If
> not, would you consider the attached patch?
I don't believe that we have a current maintainer for this backend although
we do get some submissions from Epson Japan now and then for new models. I
wonder if they would be willing to shed some light on this or provide us
some documentation on this aspect of the protocol?

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