[sane-devel] truncated image data when scanning via network

Jens Gulden mail at jensgulden.de
Thu Jul 20 20:56:42 UTC 2006


Hello sane people,

I have started using saned and network-scanning instead of connecting the scanner/printer locally 
via USB.
Unfortunately, the maximum size to scan is 210mm x 293mm for black&white scans, which is almost a 
full-sized A4 image (210mm x 297mm). Attempts to scan larger sizes strangely result in truncated 
image files on the client, the data just seems to stop at some fixed number of bytes. Scanning on 
the server (locally via USB) works fine.
Examples:

'scanimage --mode "Black & White" --resolution 300 -x 210 -y 297 > network_bw_300dpi_210x297.pbm'
network scanning:
-y 297 : 1072633 bytes (invalid file)
-y 295 : 1072633 bytes (invalid file)
-y 294 : 1072633 bytes (invalid file)
-y 293 : 1072323 bytes (VALID FILE)
-y 292 : 1068603 bytes (VALID FILE)
Data seems to be truncated at 1072633 bytes.

local scanning on the server:
-y 297 : 1076353 bytes (valid file) ...
-y 292 : 1068603 bytes (valid file)

The same occurs when scanning in grayscale, but at a different number of bytes and a slightly 
different height in mm:

'scanimage --mode "True Gray" --resolution 300 -x 210 -y 297 > network_gray_300dpi_210x297.pgm'
network scanning:
-y 297 8531237 bytes (invalid file) ...
-y 292 8531237 bytes (invalid file)
-y 291 8518837 bytes (VALID FILE)
Data seems to be truncated at 8531237 bytes.

Color scanning seems to always result in invalid files for sizes near A4.

Is this some known behaviour? I haven't found something like this in the list archive.

The pnm-headers of the truncated files are ok. There are no error messages in the logs or when 
running saned -d128. Filling up the missing bytes with zeros leads to files which can at least be 
opened by e.g. gimp (but with the last rows of pixels being just white, of course).

The scanner/printer is a Brother MFC3420C connected via USB with the SANE driver delivered by 
Brother (brscan-0.2.1-0.i386.deb). Both server and client run on Debian packages libsane 1.0.16-4, 
sane 1.0.14-1 and sane-utils 1.0.16-4.

It would be great if someone has an idea. Thanks,
Jens



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