I want to design a half band filter to filter a breast cancer image. what parameters should be considered and how to apply that filter to a given image?

 g = imfilter (b, hd)
??? Error using ==> iptcheckinput
Function IMFILTER expected its second input, H,
to be one of these types:

double

Instead its type was dfilt.dffir.

hd is the half band filter that I have used and b is the image to be filtered. but it shows error.