Lecture-07

# Butifweselectsubsamples

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: ng, in general, is understood to mean the representation of a discrete version of a continuous signal. But if we select subsamples from an already sampled image, then we are performing sampling as well. g[n] f [ Mn] • g[n] contains every Mth sample of [ n ] f 1 M g[ n ] Sampling density of sampling density of f [ n ] Ghassan AlRegib © Georgia Tech 7 Ghassan AlRegib © Georgia Tech 8 2 9/11/2012 Downsampling ECE 6258 Fall 2012 • 2‐D: In rectangular downsampling: ECE 6258 Fall 2012 General 2‐D Subsampling • Let be the downsampling matrix M g[ n ] f [ Mn ] g[n] f [ Mm, Nn] i.e. Keeping every Mth sample of every Nth row • Sampling density is reduced by a factor of | det M | 1 g[m, n] Sampling density of MN sampling density of f [m, n] M • Note: A dowsampled image by is considered as a sampled image of the continuous image by M Ghassan AlRegib © Georgia Tech ECE 6258 Fall 2012 9 General 2‐D Subsampling Ghassan AlRegib © Georgia Tech 10 Example ECE 6258 Fall 2012 1 1 M 1 1 is equivalent to Rotation 1 1 m mn g[m, n] f f 1 1 n m n Ghassan AlRegib © Georgia Tech 11 Ghassan AlRegib © Georgia Tech 12 3 9/11/2012 Downsampling ECE 6258 Fall 2012 • To find the relation between the spectra of both signals, we relate them to the analog signals: F (...
View Full Document

Ask a homework question - tutors are online