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<DIV><FONT color=#0000ff size=2 face=Arial><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 size=2 face=Arial><SPAN
class=165424000-05012013></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff size=2 face=Arial><SPAN class=165424000-05012013><A
href="http://www.scantips.com/curve2.html">http://www.scantips.com/curve2.html</A></SPAN></FONT></DIV>
<DIV><FONT color=#0000ff size=2 face=Arial><SPAN
class=165424000-05012013></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff size=2 face=Arial><SPAN class=165424000-05012013>Good
stuff.</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff size=2 face=Arial><SPAN
class=165424000-05012013></SPAN></FONT> </DIV>
<DIV><FONT color=#0000ff size=2 face=Arial><SPAN
class=165424000-05012013>R/</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff size=2 face=Arial><SPAN
class=165424000-05012013>Michael</SPAN></FONT></DIV>
<DIV><FONT color=#0000ff size=2 face=Arial></FONT> </DIV>
<DIV><FONT color=#0000ff size=2 face=Arial></FONT> </DIV>
<DIV></DIV>
<DIV dir=ltr lang=en-us class=OutlookMessageHeader align=left><FONT size=2
face=Tahoma>-----Original Message-----<BR><B>From:</B> Michael Watson
[mailto:mwatson33@comcast.net] <BR><B>Sent:</B> Friday, January 04, 2013 5:28
PM<BR><B>To:</B> 'sane-devel@lists.alioth.debian.org'<BR><B>Subject:</B> Sane
Scanimages Too Dark<BR><BR></FONT></DIV>
<DIV><SPAN lang=EN>
<P><FONT size=2 face=Arial>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 size=2 face=Arial>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 size=2 face=Arial>I do not understand why the upper limit is at
approximately 191 and not 255.</FONT></P>
<P><FONT size=2 face=Arial>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 size=2 face=Arial>[genesys] sanei_genesys_create_gamma_table: size =
256, maximum = 65535, gamma_max = 65535, gamma = 1.7</FONT></P>
<P><FONT size=2 face=Arial><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 size=2 face=Arial>Any insights appreciated.</FONT></P>
<P><FONT size=2 face=Arial>R/<BR>Michael</FONT></P>
<P><FONT face=Arial><BR><FONT
size=2></FONT></FONT> </P></SPAN></DIV></BODY></HTML>