Masking
The above image shows RegiStax after processing a set of lunar images and pressing
the CREATE MASK. The program normally starts with the "show mask" as a default but for this example I have changed it to show wavelets. Now we change to Show Mask and change the left-slider to position 58 (just inside the peak) and we get the following.
All areas that are shown in black will block the effects of wavelets fully, areas that show red of even white will be passing the wavelets like normal. The default filtertechnique is using
a lo-hi clipping system. Pixels with intensity values smaller than the lo-setting will be blocked, and the same applies for pixels larger than the hi-settings. The "feather" setting allows the user to set a transition from fully blocked to unblocked. In the above example 25 was used. For the lo-clipping (which was set at 58) this means that pixels with values smaller than 58-25 = 33 will not be affected by wavelets. Values in the range of 33-58 will be gradually showing effects of the wavelets. Notice that the crater-floor of plato is in this gradual range.
But we have another technique a user can call, Lo-HI gradient. This does not use the pixel-values as a base for the mask but calculates for every pixels how much gradient there is with the pixels surrounding it. Areas with low gradient and areas with high-gradient can be treated like the above example. The image below shows how this mask looks.
It can be clearly seen that the histogram is very different. The low value was now set to 8. This actively dims most of the effects of wavelets on the 'mare' but not fully. The areas with more gradient are located at the interesting places around the craterwalls etc and they will be fully available for the wavelets.