If, Fhp(u, v)=F(u, v) – Flp(u, v) and Flp(u, v) = Hlp(u, v)F(u, v), where F(u, v) is the image in frequency domain with Fhp(u, v) its highpass filtered version, Flp(u, v) its lowpass filtered component and Hlp(u, v) the transfer function of a lowpass filter. Then, unsharp masking can be implemented directly in frequency domain by using a filter. Which of the following is the required filter?
(a) Hhp(u, v) = Hlp(u, v)
(b) Hhp(u, v) = 1 + Hlp(u, v)
(c) Hhp(u, v) = – Hlp(u, v)
(d) Hhp(u, v) = 1 – Hlp(u, v)
I had been asked this question during an interview.
My query is from Unsharp Masking, High-boost filtering and Emphasis Filtering in section Intensity Transformations and Spatial Filtering of Digital Image Processing
