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<div class="moz-cite-prefix">On 05/01/2013 01:45, Michael Watson
wrote:<br>
</div>
<blockquote cite="mid:08A41DECF44947B990C9D3EBE1EA5D09@wat000"
type="cite">
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<div><font color="#0000ff" face="Arial" size="2"><span
class="165424000-05012013">I may have answered one of my
questions after researching the sane pages. The "curve
tool" is a transfer function graph.</span></font></div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="165424000-05012013"></span></font> </div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="165424000-05012013"><a moz-do-not-send="true"
href="http://www.scantips.com/curve2.html">http://www.scantips.com/curve2.html</a></span></font></div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="165424000-05012013"></span></font> </div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="165424000-05012013">Good stuff.</span></font></div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="165424000-05012013"></span></font> </div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="165424000-05012013">R/</span></font></div>
<div><font color="#0000ff" face="Arial" size="2"><span
class="165424000-05012013">Michael</span></font></div>
<div> </div>
<div> </div>
<div dir="ltr" class="OutlookMessageHeader" align="left"
lang="en-us"><font face="Tahoma" size="2">-----Original
Message-----<br>
<b>From:</b> Michael Watson [<a class="moz-txt-link-freetext" href="mailto:mwatson33@comcast.net">mailto:mwatson33@comcast.net</a>] <br>
<b>Sent:</b> Friday, January 04, 2013 5:28 PM<br>
<b>To:</b> '<a class="moz-txt-link-abbreviated" href="mailto:sane-devel@lists.alioth.debian.org">sane-devel@lists.alioth.debian.org</a>'<br>
<b>Subject:</b> Sane Scanimages Too Dark<br>
<br>
</font></div>
<div><span lang="EN">
<p><font face="Arial" size="2">Request insights from the brain
trust. Sane scanimage files are too dark while windows<span
class="056531522-04012013">'</span> scans (Canon drivers<span
class="056531522-04012013">/</span><span
class="056531522-04012013">applications</span>) are
fine?</font></p>
<p><font face="Arial"><font size="2">I have an archlinuxarm
box and an Lide210 scanner. Utilizing SaneTwain on a
windows box the <span class="056531522-04012013">network
</span>scans were too dark. Similarly, scanimage (local)
scans were also too dark. Trying to compensate the
SaneTwain gamma was experimented with. What worked well
was a straight line curve that maxed <span
class="056531522-04012013">out </span>at the top <span
class="056531522-04012013">while </span><span
class="056531522-04012013">3/4</span> of the way <span
class="056531522-04012013">to the right </span>(0,0
--> 191,65535 --> 65535, 65535)<span
class="056531522-04012013"> and not the top right
corner ((0,0 --> 65535, 65535).</span></font></font></p>
<p><font face="Arial" size="2">With this information the
scanimage (local) was adjusted with gamma4scanimage 1.75 0
181 255 65535, <span class="056531522-04012013">which</span>
works well.</font></p>
<p><font face="Arial" size="2">I do not understand why the
upper limit is at approximately 191 and not 255.</font></p>
<p><font face="Arial" size="2">From the sane debug it appears
the gamma is initially set to 1.7, which produces dark
image<span class="056531522-04012013">s</span> because the
initial gamma table is equivalent to gamma4scanimage 1.7 0
255 255 65535?</font></p>
<p><font face="Arial" size="2">[genesys]
sanei_genesys_create_gamma_table: size = 256, maximum =
65535, gamma_max = 65535, gamma = 1.7</font></p>
<p><font face="Arial" size="2"><span
class="056531522-04012013">Also, SaneTwain will send the
gamma table to the scanner when initially set. If it is
saved (ini file) and SaneTwain is started up, the custom
gamma table checkbox (custom-gamma=yes/no) has no
visible impact on the scanned image - too dark.</span></font></p>
<p><font face="Arial" size="2">Any insights appreciated.</font></p>
<p><font face="Arial" size="2">R/<br>
Michael</font></p>
<p><font face="Arial"><br>
</font> </p>
</span></div>
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</blockquote>
<br>
Hello,<br>
<br>
I have recently fixed an issue with gamma table handling in the
genesys backend. This should improve the darkness issue you see. To
test it you'll have to compile the latest source code available from
SANE's git repository.<br>
<br>
Regards,<br>
Stef<br>
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