Image analyzers Frequency domain

[neil phillips]

Some one asked me to post up a quick word about how to use the frequency domain filter on Image analyzer.

Go to operations on the top page. scroll down to filters. Then scroll again to Frequency domain filter

increase pen size to 20. and click view scale, up one or two clicks.

At the top of the page, dead center, you will see a large white mass. This is the image, and should be avoided at all costs, touch it with the pen and very strange things will happen to the image.

All around the image mass, you will see what looks like thousands of white spots. This is the noise in the image. The idea is to wipe this away with the pen provided. Try to wipe around the white mass in a circular motion. leaving a nice gap ( so as not to touch the image ) i leave about a inch, but you can experinment, a bit more, or less.

Once you have wiped around the image mass. You then can increase the pen size to say 60 and wipe away all of the white dots on the intire page. Once this is done press ok.

A lot of the fine grained noise caused by sharpening, should now be removed.

It works for a lot noise, but not all. It can on occasion appear to remove detail. So one has to be careful in its use. The wider the gap around the image. The safer this aspect will be.

Sometimes when you get those noise boarders after stacking in say Registax or As/2, you should crop the image before attempting the frequency domain tool.

Sometimes ( though not always ) it can affect the removal of noise grain in unusual ways. It can sometimes remove the fine grained noise caused by sharpening on lunar images too.

[Freddie]

Also be careful if you have a moon away from the planet in your image as it can do weird things with that as well.