[sane-devel] help with improving text scans

gobo gobo770 at gmail.com
Fri Dec 19 17:58:16 UTC 2008

the default for scanimage is 75dpi, and that is barely readable.  i'll
certainly give your gimp setting change a try.

but, can i also do this in the shell?  can i take an image scanned
with --resolution=150, funnel it through another utility (or two) and
end up  with a pdf containing 8.5x11" hi-res pages?

what i do now when i need a print from a scanned image:
   convert filename.pgm filename.ps
   ps2pdf filename.ps

with anything larger than 75dpi, the pdf is junk.  i can add the
-resize option to convert, and that helps, but not much.  the document
is still hard to read.

On Fri, Dec 19, 2008 at 10:51 AM, m. allan noah <kitno455 at gmail.com> wrote:
> The gimp probably defaults images to something like 72dpi. if you have
> scanned at a higher dpi, it wont know, and will print it huge. just
> change the print dpi in the gimp to match that at which you scanned.
> look in the image->print size menu option
> allan
> On Fri, Dec 19, 2008 at 11:34 AM, gobo <gobo770 at gmail.com> wrote:
>> for some time now i've been using homemade scripts with scanimage and
>> scanadf to scan my paper documents. most of my documents are plain
>> text. the results have always been poor and marginally acceptable. i'm
>> using suse 10.3 and an hp aio j6450 or psc1210xi.
>> recently i obtained a canon scanner w/adf for use at work where i must
>> use windows. to get around the image compatibility issues of microsoft
>> document imaging (office 2003) i simply print the scanned image to pdf
>> with acrobat. the results obtained with mdi are far superior to
>> anything i've ever been able to achieve with sane apps.
>> i've spent hours fumbling around with scanimage options, imagemagick
>> convert to resize the images and ps2pdf to produce the pdf files.
>> while i have made some slight improvements over the default settings,
>> i've never been able to get even close to the mdi output. in the few
>> places where i must have a good scan, i use resolutions of 150 or 300,
>> but to get prints of the image becomes a real pain. i must load the
>> image in gimp, fiddle around resizing it and then printing.
>> my standard scanimage script would contain:
>> scanimage -x 215.9 -y 297 -d
>> hpaio:/net/Officejet_J6400_series?ip= \
>> -pv --mode gray > $FILE
>> pieces from a perl script using the adf:
>> # this is the scan device
>> @scanr = ("hpaio:/net/Officejet_J6400_series?ip=");
>> # these are the command line options for scanadf
>> @opts = ("-x 215.9 -y 297 -v --mode=gray --source ADF --batch-scan=no -e 1");
>> # scan page
>> system("scanadf @opts -d @scanr -o $fnamepg");
>> adding --resolution=150, or 300 does produce a larger image, with less
>> artifacting, and much more readable, but difficult to print.
>> the answer must be one of two things -- either i'm missing something
>> real simple about producing hi-res 8.5x11" images (that is right in
>> front of my nose) or we are just not there yet with linux scanning.
>> can someone correct, or put me on a better path?
>> thanks.
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> --
> "The truth is an offense, but not a sin"

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