Fourier Transform Flashcards
(20 cards)
What is the purpose of Fourier Transform (FT) in multimedia applications?
To transform signals to the frequency domain
Which type of Fourier-related transform is commonly used in MP3 audio compression?
Modified Discrete Cosine Transform (MDCT)
In JPEG compression, which transform is primarily used on 8×8 image blocks?
DCT
What happens if a signal is sampled below its Nyquist frequency?
Aliasing occurs
What property of the Fourier Transform states that convolving two signals is equivalent to multiplying their Fourier spectra?
Convolution theorem
Which part of a Fourier Transform result is most important for spatial information in an image?
Phase Spectrum
In 2D Fourier Transform, high frequencies correspond to:
Sharp edges and fine details
In Fourier Transform terms, smoothing an image with a Gaussian filter corresponds to:
Multiplying by a low-pass filter in frequency domain
The Discrete Cosine Transform (DCT) differs from DFT primarily because:
It operates on real-valued signals and uses only cosines
Which of the following can happen due to edge effects when applying Fourier Transform on images?
Artifacts due to periodic assumptions
Which applications involve Fourier Transform in audio processing?
A) Image Deblurring
B) Speech recognition
C) Noise reduction
D) MP3 compression
Noise reduction; Speech recognition; MP3 compression
Properties of Fourier Transform include:
A) Linearity
B) Symmetry for real-valued functions
C) Non-periodicity
D) Similarity theorem
Linearity; Symmetry for real-valued functions; Similarity theorem
Which problems are associated with sampling and aliasing?
A) Loss of high-frequency information
B) Appearance of false low frequencies
C) Signal enhancement
D) Need for higher sampling rates
Loss of high-frequency information; Appearance of false low frequencies; Need for higher sampling rates
Which statements are true about Discrete Fourier Transform (DFT)?
A) It assumes periodicity of the input signal
B) It generates infinite-length output
C) It produces complex-valued outputs
D) It can suffer from aliasing if sampling is insufficient
It assumes periodicity of the input signal; It produces complex-valued outputs; It can suffer from aliasing if sampling is insufficient
Effects of applying Gaussian smoothing in the frequency domain include:
A) Reduction of high-frequency components
B) Enhancement of sharp edges
C) Low-pass filtering
D) Noise suppression
Reduction of high-frequency components; Low-pass filtering; Noise suppression
In 2D-DFT, high frequencies:
A) Are located farther from the center
B) Represent fine details
C) Represent average color
D) Can be visualized along horizontal and vertical axes
Are located farther from the center; Represent fine details; Can be visualized along horizontal and vertical axes
In image compression (e.g., JPEG), after DCT, what steps are applied?
A) Quantization
B) Zigzag ordering
C) Entropy Coding
D) Deconvolution
Quantization; Zigzag ordering; Entropy coding
In Fourier Transform applications to CNNs and deep learning, FFT is used to:
A) Accelerate convolution operations
B) Perform dimensionality reduction
C) Speed up training
D) Enhance activation functions
Accelerate convolution operations; Speed up training
Fourier Transform helps in augmented and virtual reality (AR/VR) by:
A) Real-time filtering of images
B) Spatial audio rendering
C) Gesture recognition
D) Increasing network bandwidth
Real-time filtering of images; Spatial audio rendering; Gesture recognition
Inverse filtering in imaging aims to:
A) Smooth the image
B) Undo blurring effects
C) Recover original signals
D) Enhance edges
Undo blurring effects; Recover original signals
