FREQUENCY DOMAIN PROCESSING (LAB 4)

Welcome to lab 4! What on earth we are going to learn today? Well, its all about Frequency domain processing.

What you need to understand for lab 4?

1. DISCRETE FOURIER TRANSFORM
2. LOWPASS AND HIGHPASS FREQUENCY DOMAIN FILTERS

Tips: Always ask yourself  WHAT & HOW question to make sure you understand this lab exercise.

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Discrete Fourier Transform(DFT)

• Concept: any waveform that can be constructed using a sum of sine and cosine waves of different frequencies.

• Equation : 

(2d DFT)

(Inverse 2d DFT)

• MATLAB CODE

• Relation between DFT with Spatial Domain Filtering

The results is very similar after filtering in the condition of they both have negative values, use absolute function to get rid of negatives and threshold into a binary image. This are the results.