# Questions tagged [2d]

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### Calculate sampling lattice matrix in 2D

The pattern in which the sample points are distributed in 2 dims, is called a sampling lattice, and can be defined by a generator matrix.. In 2 dimensions, the generator matrix consists of 2 vectors. ...
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### how to interpret the 2D FFT

I know how to compute the 1D FFT (and interpret values from 0 to Nyq). When computing the 2D FFT, do we compute the FFT of row then the FFT of row then the FFT of row up to the last row. ...
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### Show That a 2D Linear Transform $T \left( \cdot \right)$ Is Homogeneous

By my understanding, a transform T is homogeneous if T = 0. Then to prove that a linear transformation is homogeneous we say that: T[ax(n1, n2) + bx(n1, n2)] = aT[x(n1, n2)] + bT[x(n1, n2)] What ...
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### Mathematical Approach to Detect If a 2D Signal Is Separable

In the Special 2-D Sequences page the following examples are demonstrated, 2D dirac 2D diagonals 2D unit step function Is there a more defined method or series of steps for determining if a ...
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### 2-D low pass filter

I have an ultrasound signal that is 1536x128. I first downsample the signal by a factor of 2x2 in x and t, then I upsample the missing data with zeros, then I do an fft, fftshift, then another fft to ...
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### How is 2D convolution calculated?

I wish to implement the 2D convolution on an FPGA, so Ineed to understand how it is calculated in practice. The main difficulty that I found apparently 2 different ways showcases how to do it. The ...
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### Require explanation for Matlab freqz2

Question I browsed the code of the Matlab freqz2 function (to find out how it is different to simple fft2.) First of all it ...
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### What are the Red-Black Wavelets transformation for color (RGB) images?

I am looking for Red-Black Wavelet transform implementation on internet but I am unable to find it. Or How wavelets can be used for Images. Please help if you know how wavelets can be used for images.
287 views

### Efficient implementation of 2-d circularly symmetric low-pass filter

How can a two-dimensional ideal circularly symmetric low-pass filter or its approximation be efficiently implemented on data sampled on a square grid? I'm referring to an ideal filter with a spatial ...
11 views

### 2D Fourier Synthesis (IDFT) not yielding expected result

I am trying to recover a 2D signal using inverse DFT, to my understanding the IDFT outputs the coefficients of the fourier series of the original function up to the Nyquist frequency. So for example ...
304 views

### Zero padding and 2D Fourier transforms: how does zero-padding affect phase?

It's pretty clear that zero-padding an image before performing Fourier transform simply enlarges the magnitude image (stretching it to the new, padded size). What I can't understand is how it affects ...
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### How do I implement the CDF wavelet inverse?

I understand and have implemented a 2D discrete wavelet transform that uses a Haar wavelet to process images. Now I would like to implement a 2D Cohen-Daubechies-Feauveau wavelet transform, but I am ...