Question

While performing the median filtering, suppose a 3*3 neighborhood has value (10, 20, 20, 20, 15, 20, 20, 25, 100), then what is the median value to be given to the pixel under filter?

(a) 15

(b) 20

(c) 100

(d) 25

The question was posed to me during an online interview.

My question is taken from Smoothing Nonlinear Spatial Filter in division Intensity Transformations and Spatial Filtering of Digital Image Processing

Answer 1

Correct option is (b) 20

For explanation I would say: The values are first sorted and so turns out to (10, 15, 20, 20, 20, 20, 20, 25, and 100). For a 3*3 neighborhood the 5th largest value is the median, and so is 20.