I have a signal that contains three distinct images, this means that I have three frequencies or peaks, and each one corresponds to a picture.
I have a function that converts a signal into an image. I'm using the low pass, high pass, and band pass filters in Matlab to filter out the frequencies I want. When I use the LP filter, the image I get is clear. But when I use both the HP and BP filter, the images I get are not clear/(contain noise?). I'm using the "butter" and "filter" functions. I'm not really sure how to clear up the images or if I'm doing the wrong steps. What I'm doing is using the filter, then using a tdft function, then I plot that and use the signal-to-image function I have to get the image. I'd appreciate any help.
Signal with all three images:
TDFT of image:
First image after lowpass:
Second image after bandpass: