HW 4, EECS 203A

Problem 4.7

Nasser Abbasi, UCI. Fall 2004

Question

What is the source of the nearly periodic bright points in the horizontal axis of the spectrum in fig 4.11(b)

Solution

High frequency will show up at places when data exhibits large spatial changes such as an edge or noise. in 2D, A horizontal bright line in the spectrum indicate an edge or some sort of large gray level change in the vertical direction in the image. And vitrecal bright line in the spectrum indicate an edge or some sort of large gray level change in the horizontal direction in the image.

Periodictiy appears in the spectrum when those changes in the image happen at reqular spatial intervals.

So, looking at the image, the set vertical lines below the big letter 'a' exhibit large periodic frequency change at reqular intervals. Hence these lines are the cause of the periodic bright point in the spectrum.