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<H3><A NAME="10_18_1">10.18.1 Enabling anti-aliased lines</A></H3>
<P> Anti-aliased lines are enabled by calling the method <A href="../ref/Image.html#_IMAGE_SETANTIALIASING">
 SetAntiAliasing()</A> in the <A href="../ref/Image.html#_C_IMAGE">
 Image class</A> in the script where you want to use anti-aliasing.</P>
<P> The anti-aliasing for lines works by &quot;smoothing&quot; out the edges on
 the line by using a progressive scale of colors interpolated between
 the background color and the line color.</P>
<P><DIV class="note"><B>Note:</B> The algorithm used for anti-aliasing
 of lines is quite simple. It would be possible to achieve even better
 result by doing some real 2D signal processing. However, doing real
 time 2D signal processing on a HTTP server would be foolish so the
 design is deliberately kept simple. To achieve best visual result
 always use a dark line color on a light background.</DIV></P>
<P> An example will show that this, quite simple algorithm, gives a
 reasonable good result. The figures below shows a radar plot with and
 without anti-aliasing.</P>
<P><DIV class="example">
<BR> <A href="exframes/frame_radarex8.html" target="blank"><IMG border="0"
HEIGHT="200"  src="img/radarex8.png" WIDTH="300"></A>
<BR><B>Figure 170:</B> Spiderplot without anti-aliasing <A href="exframes/frame_radarex8.html"
target="blank">[src]</A>&nbsp;
<P></P>
</DIV></P>
<P></P>
<P><DIV class="example">
<BR> <A href="exframes/frame_radarex8.1.html" target="blank"><IMG border="0"
HEIGHT="200"  src="img/radarex8.1.png" WIDTH="300"></A>
<BR><B>Figure 171:</B> Spiderplot with anti-aliasing <A href="exframes/frame_radarex8.1.html"
target="blank">[src]</A>&nbsp;
<P></P>
</DIV></P>
<P></P>
<P> One thing you need to keep in mind when deciding to use
 anti-aliasing is that it could have potentially a dramatic effect on
 the time it takes to generate the image. Line drawing with
 anti-aliasing turned on is roughly 8 times slower than the normal line
 drawing so treat this feature wisely.</P>
<P> Furthermore there are a couple of &quot;gotchas&quot; you should be aware of
 when using anti-aliasing.</P>
<OL>
<LI> Anti-aliased lines uses up more of the available color-palette. The
 exact number of colors used is dependent on the line-angle, a near
 horizontal or near vertical line uses more colors (number of lines with
 different angles uses more colors). Hence it might not be possible to
 use anti-aliasing with color-gradient fill since the number of
 available colors in the palette might not be enough. A normal palette
 can keep around 256 colors. This means that you are advised to use a
 true-color image when using anti-aliasing.</LI>
<LI> Anti-aliasing does not work very well together with background
 images since it assumes a the same solid color on each side of the
 line. Doing a more advanced anti-aliasing algorithm would simple take
 to much processing power.</LI>
<LI>Anti-aliased lines will ignore the line width specified. They will
 always have a width of roughly 1.</LI>
</OL>
<P></P>
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