0
votes
0answers
13 views

Does the enlarged photo benefit from shrinking it?

Take a look at the following diagrams: The original picture: The upscaled (2x, bilinear) picture: In both cases the first item in first row is the input image. There is it's 2d fft next to it. ...
0
votes
0answers
12 views

What's the use case and explanation of frequency-domain subsampling?

In my solution to a certain problem I use subsampling in the frequency domain. Amazingly, it produces good results. Is it really that awkward to see subsampling in frequency domain? What the ...
0
votes
0answers
5 views

Kalman filter for velocity estimation from acceleration and displacement: constant-acceleration assumption

I have implemented a Kalman filter to estimate the velocity knowing the acceleration and the positon measurements as explained in this Q/A: Estimating velocity from known position and acceleration ...
0
votes
0answers
10 views

homography matrix problem

i have mini project to do about homography , but i am really a beginner in matlab . i have calculated the homography matrix easily by taking a set pixels from both images but the problem is how to ...
0
votes
0answers
7 views

Inferring space domain signal from 2D DFT

By just looking at the 2D Fourier Transform of a signal, can it every be known precisely which values in the space domain are zero?
0
votes
1answer
18 views

Upscaling detection approach

I'm trying to implement a solution that would, to some extent, evaluate a picture telling what are the chances that it was upscaled from the smaller image. My approach is as follows: Take a picture ...
0
votes
0answers
12 views

Help in solving the expression of EM

An FIR system is excited by a nonlinear deterministic signal $z_n$. The output of the system is corrupted by zero mean additive white Gaussian noise and this is observed, i.e., $y_n = \mathbf{h^Tz_n} ...
1
vote
1answer
30 views

Calculation frequency response of digital filter with known structure

Short question What are main stages (steps) of calculation frequency response of digital filter by their structure? Detailed question Let suppose that there is discrete FIR filter with known ...
0
votes
0answers
35 views

What is the 2D Fourier Transform of this function?

$ f(x, y) = \begin{cases} 1,\hspace{30px} x > 0 \\ 0,\hspace{30px} else\\ \end{cases} $ i.e. $f(x,y)$ is a bi-variate function which is zero everywhere to the left of the y-axis and one ...
0
votes
0answers
6 views

Time Lapse Video Analysis: Changes in Light Quality

I am working with a set of hundreds of simultaneously recorded time-lapse videos, and I want to be able to quantitatively determine which frames show the transition from night to dawn and day to dusk ...
3
votes
2answers
43 views

Question about Q matrix (noise process covariance) in Kalman filter

I am implementing my own discrete Kalman filter to estimate velocity from acceleration and position measurements (using Matlab ). I think I managed to deal with the $R$ matrix (measurements noise ...
0
votes
0answers
15 views

Running 2D array through FFT in matlab

I have an input file that is a 2D array but don't know how to convert code that I have to accept the original file and bandpass filter around 18-20 for frequency and then create the bandpassed output ...
0
votes
1answer
21 views

Contrast stretching Equation problem

How to determine $a$ and $b$ in this equation. I know how to determine $c$ and $d$ by looking at the intensity histogram. But what about $a$ and $b$ ?
0
votes
2answers
29 views

Confused about anti-aliasing in analog filters

I'm a newbeginner when it comes to signal processing. I'm reading up about anti-aliasing, Nyquist and band-pass filters. There's something I don't get: Anti-aliasing in analog filters. Lemme try to ...
0
votes
2answers
43 views

best implementation of a real-time, fixed-point iir filter with constant coefficients

I have implemented IIR filter in direct form, parallel form, and cascade form. The input in all the cases is a kronecker delta function. How to judge which implementation is better is in real time and ...
-1
votes
2answers
47 views

can MFCC coefficients alone be used to do voice detection?

Aim of my project is to differentiate between cases of silence, single active speaker and multiple ( simultaneous ) active speakers using as basic ( but effective ) logic as possible. Is it possible ...
0
votes
1answer
24 views

What does one call this method of grid fitting?

The input space has artefacts that are already in a grid-like layout: I'd like to be able to fit/draw a grid over the artefacts so as to separate them, preferably with lines on average mid-way ...
2
votes
1answer
42 views

How to analyse Phase spectrum of 2D signals?

I am beginner in image processing. When I applied Fourier transform on two images say Lena and Cameraman etc., I obtained magnitude and phase spectrum for each one. I want to concentrate on phase ...
-1
votes
0answers
41 views

Convolution Between Signals

How can I find the convolution between $$ g_1(t)= \cases{\int A/\sqrt{T}, & 0<t<T/2\\ -A/\sqrt{T}, & T/2<t<T \\ 0, & elsewhere } $$ and $$ g_2(t)= \cases{-\int A/\sqrt{T}, ...
0
votes
0answers
23 views

energy and power type signals [duplicate]

How can I determine if the signal $$\begin{array} \\g_1(t)=A\cos (2\pi f_c t), & \frac{-T}{2}<t<\frac{T}{2} \\ 0, &\text{otherwise} \end{array}$$ and: $$g_2(t)=\cos(t), -\infty < ...
0
votes
0answers
11 views

Developing Python code for BPSK Fiber Opticis Communication

I am a beginner both in Python and DSP but eager to take my first assignment tasks. I need to implement BPSK fiber optics communication simulation technique in Python. As per my research I found ...
0
votes
0answers
22 views

Signal Processing using Fourier Transform1 [duplicate]

How can I derive the fourier transform of ...
0
votes
1answer
60 views
0
votes
1answer
16 views

LPF - signal values unaffected at specific times

Is it possible to design an LPF that has an output identical to the input at specific points in time domain (the rest of the input waveform can get filtered/distorted)? Is there a general ...
0
votes
0answers
11 views

Finding peak width (FWHM) using Python on a multi-peak dataset [on hold]

Here's my denoised data: I've calculated my peaks, but if I define the peak width as full width at half maximum (FWHM) (while assuming zero is defined as the smallest point in data between ~25 to ...
1
vote
2answers
48 views

DFT vs FFT: does odd number works for DFT only?

I am always confused between FFT and DFT. In both algorithm, it has been assumed that the signal is periodic (so my understanding is that, if you have a 20 sample point signal, and you do DFT or FFT, ...
1
vote
1answer
22 views

Manual Extraction of Filter Phase Response with MATLAB using sweep sine

I'm currently at a loss for why my code seems to not be working. I'm doing a sine sweep on a filter to calculate its freq and phase response. The frequency response checks out, however the phase ...
0
votes
0answers
14 views

Matlab: Help in learning Kalman filter for parameter and state estimation

I have AR(1) model with data samples $N=500$ that is driven by a pseudo random binary sequence $x$. THe observation $y$ is corrupted with measurement noise $v$ of zero mean. The model is $y(t) = ...
0
votes
1answer
27 views

Circle detection opencv

I Would like an explanation of the parameters for opencv's HoughCircles function. I'm new to image processing in general and I have recently started using opencv. ...
1
vote
1answer
28 views

How does sampling and subsequent resampling affect aliased harmonics?

If I sample a signal with a harmonic higher than half my sample frequency I can predict the aliased frequency easily as $$|F_h-kF_s|$$ But what if after sampling the signal, I re-sample at a lower ...
1
vote
1answer
29 views

What preprocessing technique can help me to filter the background text noises using matlab…the image is shown below?

Can anyone help me to improve the degradation of the following image....i am working on OCR system in Amharic language and what is the best image filtering technique that can help me to separate ...
0
votes
1answer
17 views

How to determine stopband of discrete Gaussian, stdev sigma, support N

I would like to analyse a gaussian smoothing kernel with a set standard deviation and support (let's say, in MATLAB, fspecial('gaussian', [5 1], 1.3) so sigma is 1.3 and support is 5) in the DTFT ...
2
votes
1answer
51 views

Is image reconstruction possible using its magnitude only?

Let us take any image like Lena or cameraman. I know that when Fourier transform is applied on image,spatially global features like amplitude and phase are obtained locally. My question is whether it ...
0
votes
0answers
9 views

How to programatically perform image segmentation in real-time

I am currently trying to segment ultrasound images of blood vessels (video frames), such as the one directly below. Using a simple binary filter on the saturation channel (code below), I can get a ...
0
votes
1answer
18 views

Correction of signal after High-pass RC-filter

I have one question about digital correction of signal after RC filter which is high-pass. Let me explain detail. I have one simple signal conditioner. It has RC filter on the signal input with ...
0
votes
0answers
24 views

DFT and Inverse DFT in Image Processing

I have implemented DFT from this link. 1) Tried taking dft for the three Channels(R, G and B) and reconstructed the original image by taking inverse dft for all three channels and merged them ...
0
votes
1answer
45 views

I saw this question on one of the sites related to DFT

The analog signal x(t) is band-limited to 40 Hz. Suppose the signal is sampled at the rate of 100 samples per second and that at this rate 200 samples are collected. Then 200 zeros are appended to the ...
0
votes
1answer
44 views

Multi-image denoising

I have two signals Sa and Sb, both affected by the same noise. I don't know how much noise is mixed into each one, and the signal+noise is transformed using some (unknown) nonlinear function before I ...
2
votes
0answers
18 views

Determining the point in a temporal signal when a periodic behavior begins to occur

I'm a newcomer to digital signal processing, so I'm looking for some general advice and direction on this problem I have. I have a signal like that shown below. Starting around x=40000, you can see a ...
2
votes
0answers
37 views

Matlab: Help in learning EKF

I have AR(1) model with data samples $N=500$ that is driven by a nonlinear input $x$. THe observation $y$ is corrupted with measurement noise $v$ of zero mean. The model is $y(t) = ay(t-1) + x(t) + ...
0
votes
0answers
11 views

2D IIR filter design (x-axis width proportional to y-axis)

I want to design a 2D IIR filter (that is, created line-by-line progressively). What is the best way to go about this? I would like the response to look something vaguely like this: The actual ...
1
vote
2answers
52 views

Best Car Recognition Algorithm

Could anyone suggest the best algorithm for a real-time Car recognition (say in a parking space)? I am planning to implement the same on FPGA as well. Kindly suggest. Thank you.
0
votes
1answer
31 views

Phase is not linear in frequency domain after delay in time domain

When impulse response is symmetric around sample zero phase entirely zero. in = 0 , 0 , 0 , 0 , 1 , 1 , 1 , 1 , 0 , 0 , 0 -> This gives zero phase result As I know if I apply a delay in time ...
0
votes
0answers
17 views

Relation between Gaussian and Savitsky-Golay kernels

I would like to make a mathematical comparison between two methods in my field. One smooths with a Gaussian filter, and one smooths using a second-order Savitsky-Golay filter. Let's say the window ...
0
votes
0answers
11 views

Question concerning fading property

I have a question concerning an article I've juste read: "Estimation of Ricean and Nakagami Distribution Parameters Using Noisy Samples" by Beaulieu and Chen. The authors give the probability density ...
0
votes
0answers
39 views

How to check whether a continuous signal is periodic or not?

How to check if a continuous signal is Periodic or not? My notes says $\cos(\frac{3}{2}\pi t)$ is periodic because $T=4/3$. And $\cos(\frac{3}{2}t)$ is not periodic as $T=4\pi/3$.
0
votes
0answers
17 views

Is it possible to auto compute for the optimal value of Lagrangian multiplier?

Consider the cost function $f(X,\lambda) = \|AX-b\|_2^2 + \alpha \|LX\|_2^2$ $A:$Measurement matrix($R_{m\times n}$,$m \ll n$), $b:$observation vector($R_m$), $L:$Laplacian operator($R_{n \times ...
0
votes
1answer
15 views

Significance of Lambda in Basis pursuit

In basis Pursuit,l1 minimization is done to perform compressed sensing.In the literature there is a lamba parameter used as a regulizer. What is its significance?
0
votes
0answers
12 views

How to use Kernel of Pattern recognition in c++? [on hold]

I am having a code for Sparse representation classification for Face recognition in c++. I wanted to use Kernel trick to perform Kernel sparse representation classification. Please suggest some ...
0
votes
2answers
49 views

Phase response of FFT in practice

As I know if the impulse response is symmetric around sample zero phase response should be entirely zero. The code below just set a rectangular window for vector "in" ...

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