You can low-pass an image by using the Smooth module with any one of the methods listed there, several of which you can specify the size.
For high-pass filtering, you can do this in an automated way using the RunImageJ module. Any process that you can write a macro for in ImageJ ought to work with RunImageJ in CP. In ImageJ, I used Plugins > Utilities > Find commands, and searched for “pass”; the Bandpass Filter plugin came up. To get the macro commands from ImageJ, I ran Plugins > Macros > Record, then proceeded to use the Bandpass Filter. The output was this:
run("Bandpass Filter...", "filter_large=40 filter_small=3 suppress=None tolerance=5 autoscale saturate");Now in CP, choose Macro in RunImageJ. Put the above commands into the Macro window, set the “Current image” setting to the image of choice, and you will get something akin to the attached image. The caveat is that you have to know the filter sizes in advance.
Hope this helps!