Noise filtering

Figure 13: The widget for noise filtering

See Fig. 13. First choose, if you want to have a 1D power spectrum displayed, which shows the frequencies present in all scan lines added up incoherently, or the 2D fourier transform of your image. You can then drag the mouse over the frequency area to be filtered out and choose which type of filter to use. You can either Smooth out a spike (1D only), Kill it, or apply a second order Butterworth (BW) or a Gaussian filter of chosen width. In the 2D case, you can have the fourier transform overlayed with the corresponding time frequencies (calculated over the pixel dwell), by hitting Show Frequency. Don't forget to Apply Filter.

You can have the filter of the chosen area applied to the current image selected from the list only, or to all images of same dwell. If the last filters were applied to a single image only, you can choose to Undo and thereafter Redo them or go back to the Original Image directly. For the case of a single undo, ``Apply Filter'' will become active with the last chosen frequency area (not shown), so you can reapply the last filter. This is mainly meant for testing a filter on a single image first, undo it, and then apply it to all images of the current dwell.

Hit Accept to transfer your filtering results back to the main program or choose Dismiss, if the results are unsatisfying.