Parent Topic: <A href="http://www.pcigeomatics.com/cgi-bin/pcihlp/IWORKS|Filter">Filter</a><hr>
<H4>Edge Sharpening Filter</H4>
This filter uses a subtractive smoothing method to sharpen an
image. First an average filter is applied to the image.  The
averaged image retains all low spatial frequency information but   
has its high frequency features, such as edges and lines, attenuated.
Consequently, the averaged image is subtracted from its original
image and the resultant difference image will have primarily the edges
and lines remaining.  After the edges are determined in this manner, 
the difference image is added back to the original image to give an 
edge enhanced image.  The resultant image will have clearer high 
frequency detail; however, there is a tendency for noise to be 
enhanced, as might be expected.<p>
NOTE: In order to filter pixels located near the edges of the image, 
edge pixel values are replicated to give sufficient data.
<P>
<hr>
Parent Topic: <A href="http://www.pcigeomatics.com/cgi-bin/pcihlp/IWORKS|Filter">Filter</a><br>
<a href="http://www.pcigeomatics.com/dev_corner/pcihlp_gateway.html">About PCI Help Gateway</a>