Editing Digital image processing (section)

==== Image padding in Fourier domain filtering ====

Images are typically padded before being transformed to the Fourier space, the [[highpass filter]]ed images below illustrate the consequences of different padding techniques:

{| class="wikitable"
|-
! Zero padded
! Repeated edge padded
|-
| [[File:Highpass FFT Filtered checkerboard.png]]
| [[File:Highpass FFT Replicate.png]]
|-
|}

Notice that the highpass filter shows extra edges when zero padded compared to the repeated edge padding.