The idea of this class is to test if the Sun's implementation multistep image scaling (using either
RenderingHints.VALUE_INTERPOLATION_BICUBIC or RenderingHints.VALUE_INTERPOLATION_BILINEAR)
This code is very inspired on Chris Campbells article "The Perils of Image.getScaledInstance()"
The article can be found here:
http://today.java.net/pub/a/today/2007/04/03/perils-of-image-getscaledinstance.html
Note that the filter method is threadsafe