[sane-devel] "stop and go" and colour lines with epson 1250

[m. allan noah]

if this scanner is usb 1.1 and capable of jpeg compression in hardware, 
that might explain the difference, since color scans at anything above 200 
dpi can usually fill the usb. windows might use the jpeg compression, and 
sane might not.

another possible cause might be usb packet timeouts. are there any error 
messages in /var/log/messages?

but i dont know much about epsons...

allan

On Fri, 7 May 2004, Prakash K. Cheemplavam wrote:

> Hi,
> 
> I am using sane-backends 1.0.14 with epson 1250 scanner and have 
> following problem:
> 
> When I try to scan with higher dpi (eg 600, but starts at 240dpi 
> already) the scanning process isn't done in one go. It is more like 
> scan-pause-scan-pause-scan-pause...etc. Not only the speed suffers by 
> this, but also the quality: Sometimes at the pause points i get 
> horizontal coloured lines which don't belong there. (using xsane)
> 
> I am using libusb 0.18 with 2.6.6-rc3-mm2 based kernel, but I tested an 
> old 2.6.0-test11 kernel on other hardware, as well, here with libusb and 
> scanner module and both at least show the "stop and go" symptom. (I 
> haven't checked image quality. (Tested with scanimage)
> 
> It seems xsane does more of that stop and goes than scanimage, but I 
> haven't thoroughly tested it.
> 
> 
> As a check I tried to scan in windows and here there is no problem. The 
> scan is done in one shot, so it is fast and the quality is great here - 
> so it is not a hardware problem.
> 
> 
> SO I wonder what the problemin Linux is. I don't remember correctly 
> whether I didn't have that problem with older sane-backends. Should I 
> try older plustek drivers? How can I easily do it?
> 
> Thanks,
> 
> Prakash
> 
> 

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