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In article <1992Oct2.203621.5649@tamsun.tamu.edu>, mchung@ee.tamu.edu
(Maranatha Chung) writes:
|> Why is an odd order FIR filter better than an even order FIR filter?
Given impulse response is symmetric about its center, the group delay
is
(filter length - 1)/2.  For an odd length filter, the group delay would
be an integer.  For an even length filter, the group delay would be
fractional.

Some applications in image processing need to know where to chop off the
convolution header and tail so as to preserve pixel dimensions.  Linear
phase and an integer group delay make it easy to truncate the larger,
convolved image.  

   mchung@ee.tamu.edu (Maranatha Chung) writes:

   From: mchung@ee.tamu.edu (Maranatha Chung)
   Organization: Texas A&M University
   Sorry if this has been asked before.

   Why is an odd order FIR filter better than an even order FIR filter?
   Thanks.

It is not, both are equally good.  The only difference is the group
delay.  For an odd length fir filter the group delay is (N-1)/2, note
that this results in a integer number of sample delays.  For an even
length filter the group delay is also (N-1)/2, but the delay is NOT
integral.  If this makes even length filters worst that odd then I
guess this answers your question...


Jeff Warner