dataset can also be increased by co-registering the data with other remote sensing or
GIS data available.
14.5.1 Speckle Reduction
The problem of speckle in SAR imagery has been addressed in previous chapter,
and the multi-look concept to improve speckle reduction in the signal processing
domain has been introduced in previous section in the image analysis domain,
further speckle reduction may be achieved by using smoothing algorithms, or
filters. Among the variety of filters available, four examples are introduced in the
following discussion.
Average filtering is a very simple way of reducing the appearance of speckle. A
window of x-number of rows and y-number of columns within the image matrix is
selected. It is usually 3 by 3 or 5 by 5 pixels in size. The intensity of the centre pixel
of the defined window is then replaced by the average value of all pixels around
it. By sliding this filter window along the rows and columns of the image matrix, a
Fig. 14.3 Enhancement equalization
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