Ideal Highpass Filter

The Ideal Highpass Filter (IHPF) blocks off the lower frequencies which are below the cutoff frequency Do, and only lets the
higher frequencies pass. Since edges and other abrupt changes are associated with the higher frequencies so this filter causes
sharpening alongwith a decreasein global contrast of the image. The effect on the image when Do is increased can be seen below.
Also these are analogous to the highpass sharpeneing filter in the spatial domain.


`The Original Image`	`Image after using the IHPF` `with Do = 10`	`Image after using the IHPF` `with Do = 30`	`Image after using the IHPF` `with Do = 60`

`Fourier Spectra of Original Image`	`Fourier Spectra after using the IHPF` `with Do = 10`	`Fourier Spectra after using the IHPF` `with Do = 30`	`Fourier Spectra after using the IHPF` `with Do = 60`

A 3D plot of the fourier spectra after applying the IHPF
(The X - Y ranges have been modified to get a better view of the plot)

Page last updated on 28 January, 2004.	`AT cse.iitd.ac.in`	© Parag Chaudhuri , 2009