how to use pfilt to perform anti-aliasing

Dear Radiance experts,

I use pfilt to treat a .hdr image generated by rpict command.

However, the the pfilt doesn't seem to have any impact in terms of
anti-aliasing of the image.

The pfilt command I used is:
pfilt -x 1024 -y 1024 -e 1 -r 0.55 ./direct_sunlight.hdr > test.hdr

the original .hdr image (saved as png file) is:

the output .hdr of the pfilt (saved as png file) is:

Can you kindly tell me if I'm using pfilt correctly to perform