Help with filtering an image with customized filter

Hello, I am new with Image Processing in matlab. I am trying to create a Z-domain function with

[H1,w] = freqz([0.34,0.30702,0.2669986,0.1656786,-0.1343],[1,-2.092,2.41188,-1.3963880,0.44069],10000);

and then filter a blurred and noised gray-scaled lena image. This is how i blurred and noised the image: BlurredLena = imgaussfilt(Lena, 2); BlurredNoisedLena = imnoise(BlurredLena,'gaussian',0,0.005);

when i am using the filter2 function all i get is a black image. can someone help me with the code?

Thank you