Signal Processing Stack Exchange
Signal Processing Stack Exchange

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1500 questions
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STFT: why overlapping the window?

For STFT, we impose window of certain size onto the original signal, then we perform fft on each window. The uncertanty about frequency and time is determined by the width of the window, however, I can't understand what is the point of having…
kuku
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Real-Time Human Pitch Detection

I'm trying to implement a singing game that will analise raw mic input and tell the player how good is he singing. That needs to be done in real-time. I've come across a lot of threads asking the same question but I'm still quite not done with it,…
Felipe Lira
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Implementing Gaussian random variable by using a uniform random variable

I'm trying to write a C++ function that will return Gaussian random values, given their means and variances. There is a library function rand(), which returns random numbers between 0 and RAND_MAX. RAND_MAX does not have a fixed value, but it is…
hkBattousai
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What's the Underlying Algorithm for Detail Preserving Upsampling in Photoshop CC?

The detail-preserving upsampling algorithm in Photoshop CC is truly amazing. It can upscale any image while preserving details in almost real-time. And I truly wonder how it is implemented. I've started by searching papers with keywords single image…
Void Main
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Opencv calcHist and calcBackProject in plain english

i've started experimenting with c++ and opencv because of i want to learn image processing. Now, my first exercise is to create a skin detector with calcHist and calcBackProject. But i don't understand few things: the statistic interpretation of…
nkint
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What is the difference between normalized peak of correlation, versus peak of correlation divided by its average?

Given a template, and a signal, the question arises as to how similar the signal is to the template. Traditionally a simple correlation approach is used, whereby the template and a signal are cross-correlated, and then the entire result normalized…
Spacey
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Adaptive Thresholding for liver segmentation using Matlab

I need to segment liver from an abdominal CT image using Adaptive Thresholding. But I get the entire foreground separated from the background alone. I need only the liver part of the foreground separated. Check out the pdf file in…
Gomathi
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Image Processing method for spiky selection

I have an input as a 3D binary image and the preferred output below: Input: Preferred Output: What image processing methods should I look for if I am to have only the spiky object(s) remain, just like the preferred output above?
Karl
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Is this a correct interpretation of the DCT step in MFCC calculation?

This is a continuation of the discussion here. I would comment there, but I don't have 50 rep so I'm asking a new question. Here's how I understand the DCT step in the MFCC calculation process: The rationale behind it is to separate the correlation…
orangebanana3
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Savitzky-Golay filter parameters

I am trying to smooth a series of data in order to obtain a continuous function that could represent that given data set. It came out that the Savitzky-Golay method could be a good way. Now, I don't know much about smoothing and/or interpolate, but…
Py-ser
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How to create a distortion compensation filter

I am creating a channelizer that consists of a complex mixer, CIC decimator, and a FIR compensation/decimation filter. The final FIR filter may, if it matters, be implemented as more than one filter. My question is, how do I design a filter such…
Jim Clay
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How can you tell whether there's a signal (when your signal looks a lot like noise)?

This is my snoring detector again. I've gotten pretty good at detecting a signal when there's anything there -- can track from a wall-peeling snore down to breathing you can't even hear in the recording. The problem is, I can't tell when the signal…
Daniel R Hicks
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Image Recognition

Looking for an open-source system that allows commercial use to do image recognition on a massive and organically growing collection of 2-D images where the only known variations will be: Scaling size of image, The angle the picture-of-the-picture…
blunders
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Can a causal filter without phase shifts exist?

When I was studying dispersion of refraction index in semiconductors and dielectrics, my professor tried to explain that if a filter (like a dielectric absorbing some light frequencies, or an electric RC-filter) removes some frequencies, then the…
Ruslan
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What is meant by "spectral moment"?

I have consulted the almighty oracles of google and wiki, but I cannot seem to find a definition for the phrase "the moment of the spectrum". A legacy work text I am reading uses it in the following manner, defining the number of zero-crossings per…
Spacey
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