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<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
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   <meta name="Author" content="Oliver Rauch">
   <meta name="Description" content="scan, photocopy and fax frontend for SANE">
   <title>XSane - Enhancement</title>
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<br>&nbsp;
<blockquote>
<h1>
<u><font color="#009900">Enhancement</font></u></h1>
XSane uses a gamma table to do the following enhancement functions. If
the scanner supports a custom gamma table (and the option is enabled) XSane
uses the scanner internal gamma table with the scanner's maximum bit depth.</blockquote>

<center><img SRC="sane-xsane.jpg" height=416 width=270></center>

<blockquote>&nbsp;
<dt>
<img SRC="gamma.jpg" height=21 width=22><a NAME="GAMMA"></a><b> Gamma correction:</b></dt>

<blockquote>The gamma correction is a non linear correction. Black keeps
black and white keeps white
<blockquote>if the gamma value is greater than 1.0 the gray intensities
are brightned
<br>if the gamma value is smaller than 1.0 the gray intensities are darkend</blockquote>
</blockquote>

<dt>
<img SRC="brightness.jpg" height=21 width=22><a NAME="BRIGHTNESS"></a><b> Brightness:</b></dt>

<blockquote>positive values increase the brightness of the image. All values
are increased by the same value. 100% means a shift of the half value range
(on 8 bits (256 values) this means a shift of 128).</blockquote>

<dt>
<img SRC="contrast.jpg" height=21 width=22><a NAME="CONTRAST"></a><b> Contrast:</b></dt>

<blockquote>positive values increase the contrast of the image. Medium
gray keeps medium gray (8 bits: 128)
<blockquote>-100% means that all colors become medium gray
<br>+100% means that the difference between a value and medium gray is
doubled</blockquote>
</blockquote>

<dt>
<img SRC="rgb-default.jpg" height=26 width=26><a NAME="RGB_DEFAULT"></a><b> RGB default:</b></dt>

<blockquote>if RGB default is activated, all values for the color components
(red, green and blue) are set to the default values (gamma=1.0, brightness=0%,
contrast=0%). If you deactivate it, you can set different enhancement values
for each color.</blockquote>

<dt>
<img SRC="negative.jpg" height=26 width=26><a NAME="NEGATIVE"></a><b> Negative:</b></dt>

<blockquote>This option inverts the intensities (black &lt;-> white).
It is for scanning negatives.
<p>Negatives do not only have inverted colors, it also is necessary
to do a color correction for each color component because the negatives
have very different color ranges for each color.</blockquote>

<dt>
<img SRC="autoenhance.jpg" height=26 width=26><a NAME="AUTO_ENHANCEMENT"></a><b> Autoenhancement:</b></dt>

<blockquote>If you press this button XSane tries to set good values
for brightness, contrast and gamma correction independance of the selected
part in the preview window. This does work quiet well for brightness and
contrast, but the gamma correction normally has to be corrected manually.</b>
<br>If RGB default is disabled, the components for each color are set
individually.</blockquote>

<img SRC="default.jpg" height=26 width=26><a NAME="ENHANCEMENT_DEFAULT"></a><b> Enhancement default:</b>
<blockquote>Sets the enhancement values to default: gamma=1.0, brightness=0%,
contrast=0%.</blockquote>

<dt>
<img SRC="restore.jpg" height=26 width=26><a NAME="RESTORE_ENHANCEMENT"></a><b> Restore enhancement:</b></dt>

<blockquote>Restores the enhancement values from preferences.</blockquote>

<dt>
<img SRC="store.jpg" height=26 width=26><a NAME="MEMORY_ENHANCEMENT"></a><b> Store enhancement (Memory):</b></dt>

<blockquote>tore selected enhancement values to preferences.</blockquote>
</blockquote>

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