High pass (and low pass) image filters with cutoff in “cycles per image”

I'm trying to filter images (high-pass and low-pass) for a psychological experiment but I don't understand how i must relate the cutoff frequency expressed in "cycles per image" to the actual filter parameters.

In particular I need to create a high-pass filter with a cutoff freq of > 24 cycles/image and a low-pass filter with a cutoff freq of < 6 cycles/image. The image size is 128x128.

Can someone please point me in the right direction?

Answer 1

[Jonas]

habe a look into this under frequency domain filtering. there you can see several functions that can be used like fwind2() and ftrans2()

come back if you are stuck again ;-)