Description Use designfilt to design and edit digitalFilter objects. Use designfilt in the form d = designfilt (resp,Name,Value) to design a digital filter, d , with response type resp. Customize the filter further using Name,Value pairs. Use designfilt in the form designfilt (d) to edit an existing filter, d. Note. If you have a low-pass filter with frequency response H_lp(w), you can find a corresponding high-pass filter H_hp(w) by subtracting its frequency response from 1.. H_hp(w) = 1 - H_lp(w) So if you want your high-pass filter to pass from K to pi, design a low-pass, which you already know how to do, that passes from 0 to K, then use the equation above to find the high-pass frequency response, and.