We’re rewarding the question askers & reputations are being recalculated! Read more.

# Questions tagged [transform]

In signal processing, a transform is a mathematical technique to convert data in one domain to another. The most common example is using the Fourier Transform to convert data from the time domain to the frequency domain.

193 questions
Filter by
Sorted by
Tagged with
3k views

260 views

### Confusion in proof of Inverse Laplace Transform

For the proof of inverse Laplace transform, we change the integral from $\omega$ to $s$. I want to know the reason why we need to change the integral?
72 views

### Why we take Laplace Transform of functions which converged using Fourier Transform

There are several functions for which we know that Fourier Transform will exist but still we calculate its Laplace Transform. Can I know the reason why we need to take Laplace transform for which we ...
1k views

### Power Spectral Density computation and units

I want to make some calculs of power spectral densité of signal. For example a real voltage signal (physical unit : $V$) in time $g(t)$, its fourier transform $G(f)$ and $S_g(f)$. As far as I know,...
820 views

### Analysis and algorithmic complexity of the Constant Q transform

Here I am again (Implementation of the constant Q transform + property questions) :) I was reading this paper on a constant-q transform algorithm, where they managed to turn the following equation ...
102 views

### Is there an analogue of coherence between data sets related by a non-linear transformation?

Calculating the coherence (sometimes called magnitude squared coherence) between two signals indicates the presence or lack thereof of a linear transformation between the two signals. Is there an ...
538 views

### Wavelet transform wavdec returns matrix of the wrong size

I have a question regarding the wavdecand dwt functions in MATLAB. I am using ...
165 views

### Contourlet transform for image compression

Before today I had no idea there is any transform an such; I was only aware with DCT and wavelet transforms but today one of my teacher who is doing research on image processing project had told me ...
72 views

### Combining Distance Maps

I have two distance maps that describe distances from blue segment and the red segment. I need to compute a single weight map that describes transition from blue segment to the red segment. The weight ...
43 views

### How to calculate Walsh hadamard transform for image patches of odd sizes?

I was reading this paper on optical flow, which as apart of the algorithm makes use Walsh-Hadamard transform on image patches of size 2r+1. So far, where ever I have looked, I could only find that ...
207 views

### Laplace Transform of $-e^{-at}u(-t)$

I have found a problem in applying Laplace Transform to $-e^{-at}u(-t)$ I am doing these steps: $$= - \int_{-\infty}^{+\infty} e^{-at}u(-t) e^{-st}dt$$ $$= - \int_{-\infty}^{0} e^{-at} e^{-st}dt$$...
189 views

### Speech features that can be inverted?

I am trying to figure out speech features that can be inverted to recover the audio back with no loss or as less loss as possible. I am currently using the power spectrum which is completely ...
505 views

### Shifting of Shift-Invariant Wavelet Transforms

Main Question: Why would iterative wavelet/inverse-wavelet transforms cause a shift along the x-axis for undecimated (shift-invariant) wavelet transforms? I am attempting to remove backgrounds from ...
111 views

### Complex Cepstral Transform and Audio Watermarking

I am doing research in audio watermarking and have come across the paper that uses the complex transform to embed the watermark in order to improve the robustness and inaudibility of the embedded ...
230 views

### Harmonics on periodic functions [closed]

Ok I need to understand how some harmonic calculations work to apply some transforms. If I have a periodic functiion f(x). And I have the values of that function for several values of x (say x goes ...
389 views

### How to model/estimate channel in discrete time with different sampling time?

I want to estimate a channel based on LTE 3GPP EVA with given power delay profile (set of average power and delay of channel taps). ...
2k views

### When doing a Hilbert-transformation, why not simply multiplying by an exponential?

When doing the Hilbert-transformation, which is supposed to be a phase-shift by $\\-\frac{\pi}{2}$, why not simply use $\\e^{-j\frac{\pi}{2}}$ instead of $\\H(f) = -j \cdot \textrm{sgn}(f)$?
166 views

### Whether Fourier transform formula be considered as Convolution or Correlation?

The expression for Fourier transform is given as $$F(\omega) = \int\limits_{-\infty}^{+\infty} f(t) \ e^{-j \omega t} \ dt \tag{1}$$ Now, let one function be $f(x)$ and other be $e^{j\omega t}$ ...
293 views

### integration property of fourier series

Please help me sort this issue out. The integration property in Fourier series is as follows: So, for proving the above property, i took this approach: This is where my doubt is. Some books and ...
584 views

### How to transform or distort or skew a rectangular image to fit arbitrary quad

I have a rectangular image which need to transform so the image fits an arbitrary convex quad. Easy? Except I have an important constraint, the features on the original image must maintain their ...
2k views

### How to find out if a transform matrix is separable?

In image processing, when we have a series of basis images, how could we know if the transformation is separable or not? For example, I know that following bases are separable and transformation can ...
355 views

### Discrete wavelet transform

I am unable to understand the discrete wavelet transform on images. I followed Robi Polikar's tutorial and got a brief idea about the theory. But I'm unable to understand w.r.t images. Using Matlab's ...
126 views

### Confusion in basics of Laplace Transform

I have few confusions while starting Laplace Transform. So far I have studied, Fourier series and Fourier Transform. The basic difference which I found from different books is Fourier Transform is ...
224 views

### Development of Hilbert transform relationship

In the development of Hilbert transform relationships, Prof. Oppenheim has chosen \begin{equation} \int_{-\pi}^{\pi}X_R\left(e^{j\theta}\right)\sum_{k=-\infty}^{\infty}\delta(\omega-\theta-2\pi{}k)d\...
55 views

### Is there a special case in which wave atoms convert to curvelets?

I'm new to multi scale transformations. I was wondering if there is a special case where wave atom converts to curvelet transform? Can I use wave atom parameters to have curvelet properties?
133 views

### Frequency shift keying antennas

I am having trouble understanding how the antenna picks up signals that utilize FSK. Because FSK alters the frequency and most antennas pick up signals on a very select frequency, how exactly does ...
98 views

### One-bit depth audio

I have a music player which is only able to play sound with one a bit-depth of one. I can produce this by taking a song and simply boosting the signal $+100\textrm{ dB}$. Is there another approach ...
2k views

### Is DCT (Discrete Cosine Transform) of Type-2 lossless or lossy?

As I know, in general, the DCT is lossless. But I'm not exactly sure about Type-2 of DCT. Is it lossless or lossy?
106 views

### Multiplier in digital signal processing?

whenever we start working on Discrete Cosine Transform(DCT), Loeffler algorithm a key role. Furthur if we approach hardware implementation of this algorithm, we find methods based on Distributed ...