2D Fourier downsampling

1. What does a 2D FFT tell you?
2. What is a 2D Fourier transform?
3. What is downsampling in image processing?

What does a 2D FFT tell you?

2D FFT (2-dimensional Fast Fourier Transform) can be used to analyze the frequency spectrum of 2D signal (matrix) data. Conversely, 2D IFFT (2-dimension Inverse Fast Fourier Transform) is able to reconstruct a 2D signal from a 2D frequency spectrum.

What is a 2D Fourier transform?

The Fourier Transform ( in this case, the 2D Fourier Transform ) is the series expansion of an image function ( over the 2D space domain ) in terms of "cosine" image (orthonormal) basis functions.

What is downsampling in image processing?

Downsampling is the reduction in spatial resolution while keeping the same two-dimensional (2D) representa- tion. It is typically used to reduce the storage and/or transmission requirements of images. Upsampling is the increasing of the spatial resolution while keeping the 2D representation of an image.