sane-project-website/old-archive/1999-04/0163.html

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<!-- name="Dr. Andreas Bolsch" -->
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<!-- subject="Re: Scanner -&gt; printer problem" -->
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<title>sane-devel: Re: Scanner -&gt; printer problem</title>
<h1>Re: Scanner -&gt; printer problem</h1>
<b>Dr. Andreas Bolsch</b> (<a href="mailto:Andreas.Bolsch@maths.nott.ac.uk"><i>Andreas.Bolsch@maths.nott.ac.uk</i></a>)<br>
<i>Fri, 09 Apr 1999 10:15:44 +0100</i>
<p>
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The problem is that pnmtops is intended for printing pictures, i.e.<br>
there are provisions for a generous margin and a convenient 'best fit'.<br>
 <br>
Let's suppose we use a4 paper, that is 210mm x 297mm. The useable height<br>
and width are 95% (margin hardcoded in pnmtops), so 199.50mm x 282.15mm.<br>
If we'd like to center this 'window' we would use e.g.<br>
 <br>
  scanimage -d &lt;device&gt; --mode &lt;mode&gt; --resolution 150 -l5.25mm \        <br>
            -x199.5mm -t7.425mm -y282.15mm | \<br>
 <br>
Now 'dpi' must be an integral multiple of 72 for pnmtops (for otherwise<br>
the scaling algorithm does awkward things), and as we scanned with<br>
150dpi here, the scale factor is 72.0 / 150.0 = 0.48, so<br>
 <br>
  pnmtops -scale 0.48 -dpi 72 -width 8.28 -height 11.71 | lpr<br>
 <br>
does the job. Note that width and height are not used for scaling here,<br>
they just affect the centering (if they're not too small).<br>
 <br>
This gives for me reasonable copies up to a slight horizontal<br>
distortion (about 1%). The latter, however, is due to mechanical<br>
inaccuracy of the scanner as it's present even in the pnm file. <br>
 <br>
Of course, as already remarked, this method is rather slow, so in<br>
general pnmtolj is a better choice for b/w copies. However, for<br>
color ...<br>
<p>
<pre>
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<p>
<ul>
<!-- next="start" -->
<li> <b>Next message:</b> <a href="0164.html">Petter Reinholdtsen: "Re: Linking non-libtool libraries into a new backend?"</a>
<li> <b>Previous message:</b> <a href="0162.html">Dr. Andreas Bolsch: "Re: Color images - Lines mismatched ?"</a>
<li> <b>Maybe in reply to:</b> <a href="0144.html">Raymond A. Ingles: "Scanner -&gt; printer problem"</a>
<!-- nextthread="start" -->
<li> <b>Next in thread:</b> <a href="0158.html">Graham Stoney: "Re: Linking non-libtool libraries into a new backend?"</a>
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</ul>