l14 - 1 CMPEN/EE455 Lecture 14 Topics today: 1. Wraparound...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1 CMPEN/EE455 Lecture 14 Topics today: 1. Wraparound error in 2-D (circular) convolution using the DFT 2. Fast Fourier Transform (FFT) algorithm (G&W Ch. 4.11) 3 Example No zero padding Filter ( A B ) image f ( x, y ) with small ( C D ) operator g ( x, y ) symmetrical about origin (i.e., assume A >> C and B >> D ) Blindly use ( A B ) transforms to get h ( x, y ) = f ( x, y ) * g ( x, y ) (NOTE: This is very useful for filtering N N images with small mask [e.g., 3 3] filters avoids overhead of zero padding.) Question: What are good and bad points of h ( x, y )? CMPEN/EE455 Lect 14 2 f ( x, y ) = 0 outside x A- 1 and 0 y B- 1 nonzero only in an A B rectangle g ( x, y ) = 0 outside- C- 1 2 x C- 1 2 and- D- 1 2 y D- 1 2 nonzero only in a C D rectangle; assume C, D odd integers To do filtering, a. f e ( x, y ) = f ( x, y ) (We wont zero pad f ( x, y )!) b. Make g e ( x, y ) = A B zero-padded version of g ( x, y ) Requires special data organization; see NEXT PAGE!...
View Full Document

This note was uploaded on 09/24/2009 for the course EE 455 taught by Professor Staff during the Fall '08 term at Pennsylvania State University, University Park.

Page1 / 15

l14 - 1 CMPEN/EE455 Lecture 14 Topics today: 1. Wraparound...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online