I have a question about filters.butter2d_hp and lp. I have a butterworth filter MatLab code and a butterworth cutoff calculator which uses scene image size in mm, in pixels, an absolute cutoff and viewing distance for calculating butterworth cutoff. When I enter my scenes’ information it gives me a 0.0725 butterworth cutoff (128 mm image size, 250 image size in pixels, 2cpd required cutoff and 161 cm viewing distance).
I wish to do the same thing with psychopy by it apperently uses a different estimation which I cannot understand. I get an info in psychopy: f=1/(1+radius/cutoff) ^2*n). Could you please help me to understand this formula? How could I get the same butterworth cutoff value by using filters.butter2d_hp and lp?
I really need your help…