Signal Processing Stack Exchange
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1500 questions
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4 answers

Resize line art image

I want to print some line drawings on A3, but they aren't very large - around 600x800px. I tried obvious functions in Gimp, like resize then enhancing with wavelet sharpener or unsharp mask, with selective gausian blur before it, but print results…
zetah
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Amplitude of the Signal in Frequency Domain different from Time Domain

How does the Amplitude of the Signal is changed when taking the FFT of a Signal, Have a look, The amplitude had changed from 2 to 30, and Here is my code for generating the above output, f=1e3; %Frequency of Wave A=2; %Amplitude Fs = 1e6; …
Sufiyan Ghori
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Precision of Computer Vision algorithms

Let's say the task is to determine element position on image. First very important thing is correct detection of object then some algorithms of calculating position are used (for examble blob analysis). Everything depends on multiple things…
krzych
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Does it make sense to have complex numbers representing real-world audio signals?

In this course (Coursera: Audio Signal Processing for Music Applications) the professor uses an example of obtaining the DFT of a complex sinusoid: \begin{align} x_2[n]&=e^{\jmath\left(2\pi f_0 n+\varphi\right)}\quad \textrm{for}\quad n=0, \ldots,…
GrowinMan
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Measuring the contrast of an image

For a project, I want to measure the contrast of a global image. I want to compare different images to get the image with the best contrast. I know about the Weber contrast, but I need a normalized contrast value (in the range between 0-1 or…
501 - not implemented
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Oversampling and decimation: What filter to use?

I have a sensor producing (more or less) bandlimited data with a cut-off of about 45Hz, with a roll-off and AWGN. I have an ADC that samples said signal at 800Hz, with a single-pole anti-aliasing filter at about 200Hz. The problem is, I only have…
Damien
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2 answers

When is a network called end-to-end training?

In machine learning, we often see the expression "end-to-end" learning (or training). However, I do not know that it means. When is a network called end-to-end training? How to recognize a network is end-to-end learning?
user3051460
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What should be the correct scaling for PSD calculation using $\tt fft$

I would to calculate the PSD of a signal using FFT however the result do not match with periodogram command. What did was as follow…
justin
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Difference between frequency sampling and windowing method

These two filter design methods seem fairly similar. Both ask to determine a frequency response and then take a inverse DFT to get the filter coefficients. So what's the difference?
mavavilj
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How do I choose the parameters of a Kalman filter?

Suppose I want to track the position of a car in 2D. What I get as sensor data is my current position. So my state is $$\mathbf{x} = \begin{pmatrix}x\\y\\\dot{x}\\\dot{y}\end{pmatrix}$$ where $x \in \mathbb{R}$ is the position in m away from some…
Martin Thoma
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2 answers

Gaussian FIR filter with no multipliers?

What is the simplest way to implement a Gaussian FIR filter with unity gain coefficients and no multipliers? Please preface your answer with spoiler notation by typing the following two characters first ">!" Note: A Gaussian FIR filter is an FIR…
Dan Boschen
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Identifying license plate number of a thief's car from a video

Motivation: I recently had my laptop stolen, with lots of pictures of my family, research work and other very important stuff. Of course the theft has been reported, but I think people here are more competent in image processing compared to the…
User
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2 answers

Straight lines with an edge detection algorithm

I've been thinking of an algorithm for object recognition but it would relies heavily on straight non-noisy lines and as far as I know this is hard to obtain with edge detection algorithms. What's the best edge detection algorithm to obtain lines as…
Paul Exkei
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Intuitive interpretation of Fourier transform in beamforming

When applying Fourier transform in time domain the signal will be carried to frequency domain. And when we apply Fourier transform in spatial domain the signal will be carried to directivity domain. $$ D(\theta) = \sum\limits_{n =…
Kadir Erdem Demir
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Random sampling vs uniform sampling

In this paper of Lustig, he speaks about a something which appears unintuitive: sampling at random may exhibit better performance than sampling uniformly. I tried to understand this starting from page 15 of these slides, but I can't really make…
Arrow
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