Signal Processing Stack Exchange
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What is Super Resolution in the Context of Windowing?

I have been trying to understand what super-resolution is, in the context of DSP/DIP. What criteria is being maximized/minimized, and why? Most of my online searches yield super-res techniques from the optical physics stand point, however I know…
Spacey
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Intuition behind the scaling property of Fourier Transforms

The Fourier transform of $f(ax)$ is $\frac{1}{|a|}F(\frac{u}{|a|})$. So the frequencies are scaled horizontally but the magnitudes are also scaled when the graph of $f$ is scaled horizontally. On the other hand the fourier series of $f(\theta)$ on…
user782220
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Wang Transformation

I'm essentially a math student working on algorithms for a chemistry problem involving rotational spectra, and I keep coming across references to Wang transformations but have been unable to track down what the Wang basis is. You can assume I have…
Michael Conlen
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Loudness of PCM stream

I'm receiving PCM samples through stream which is one channel, 8000 samples per second. I figured out way of finding out loudness by calculating 'force' of signal by adding abs value of every next 1000 samples and then dividing by samples count…
solgar
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Issues related to entropy

I have long been faced with the confusion regarding entropy and would be obliged if the following are answered in less technical jargon. Following the link Different kinds of entropy raises the following questions Entropy- It is desired that the…
user1214586
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Audio normalization

I have a recording in pcm format and I want to do some simple analysis. I have some questions about what is normalization. As far I understand it is to get all the amplitudes between a range i.e. [-1, 1] The obvious way to do that is: max_amplitude…
gosom
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How do I numerically calculate a function from its noisy gradient?

I have the model $\ s(x,y)=x^2+y^2, 0 \leq x \leq 1, 0 \leq y \leq 1 $. Instead of observing the model directly I am observing the derivatives of the model + some noise (e): $\ p(x,y)=s_x+e, q(x,y)=s_y+e$ From measurements of p(x,y and q(x,y) I…
Andy
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determine two signals with a scale factor

Suppose I have 2 signals from function $f_1(x)$ and $f_2(x)$, respectively, and assume the sampling rate is above Nyquist frequency, so we can restore the underlying functions $f_1(x)$ and $f_2(x)$. But my question is, from the 2 signals, how to…
chaohuang
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MATLAB, How to filter a discrete signal?

I have a 1-by-10000 matrix of double`s stored in a file named "fecg.mat". The matrix represents the magnitude of a recorded FECG signal. I've plotted it against time (from 0 to 9999): For removing the baseline I wonder if I can use a high-pass…
hoo_man
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Does this lowpass filter have a noncausal impulse response?

I'm doing some measurements with my sound card, I have one output channel connected to one input channel. I then send the sound card a unit impulse, i.e. a signal 1 value followed by zeros. The recorded response is shown below. I know that the…
Lance
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Standard deviation of spectral flatness -- so what am I measuring, conceptually?

In my never-ending quest to identify snores, I've found that "spectral flatness" seems to be a fair measure of signal "quality". I'm computing spectral flatness as the geometric mean of the FFT power $(R*2 + I*2)$ data points divided by the…
Daniel R Hicks
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complementary IIR filters

I would like a pair of complementary IIR filters (lowpass/highpass). By complementary, I mean, when the output from the two filters is summed, the original signal is recovered. I thought I could build such pairs with butterworth filters but using a…
Bjorn Roche
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Why is PSNR used for image quality metrics instead of SNR?

I have been trying to determine why is PSNR used instead of SNR for image quality metrics? I have read through several books and most just say that PSNR is used instead of SNR, but don't give a reason as to why. I also read these posts: Signal…
Veridian
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Understanding values saved in WAVE file

The values that one can find in a wave file, e.g. 0.0036 0.0026 0.0174 0.0050 0.0026 0.0108 0.0154 -0.0114 -0.0006 0.0115 are - as I assume - relative values between -1 and 1, the range you normally see when…
me.at.coding
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OpenCV detectin skin colour invariant with illumination changes

I have to capture skin colour independent of illumination. I used the following criteria(using hsv and rgb) but it ain't working: int h = get_hue(...); int s = get_saturation(...); int r = get_red_component(...); int g =…
Roney Island
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