Signal Processing Stack Exchange
Signal Processing Stack Exchange

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1500 questions
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7 answers

How to implement a moving average in C without a buffer?

Is it possible to implement a moving average in C without the need for a window of samples? I've found that I can optimize a bit, by choosing a window size that's a power of two to allow for bit-shifting instead of dividing, but not needing a buffer…
tarabyte
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How to remove the noise without destroying the main edge?

I am working on a project. I want to segment a logo from a car and the picture's size is 3648*2432. The logo is selected by the red rectangle. I extracted this area and turn into gray level. The area's size is 249*173. Then, I use histogram…
Kuo
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Suggested Preprocessing methods for OCR on Circular Images

Hello this is my sample image I am going to do real time character detection on images like that. I've tried SURF, SIFT, MSER and template matching on original image without any preprocessing. I can detect characters but when the image changes this…
Anar Bayramov
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How to Determine Covariance Matrix $Q$ and $R$ in Kalman Filter

I am implementing getting orientation from smartphone. I want to use Kalman filter and should determine process noise covariance matrix $Q$ and measurement noise covariance matrix $R$. (newbie to Kalman filter) I don't have any idea how to determine…
jakeoung
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Determining optimal binary decision rule threshold from observations with unknown priors?

Given only observations of a binary signal perturbed by Gaussian noise with unknown prior information, how can I estimate the optimal decision threshold? ( No, this is not a homework question) Specifically, I am think about the following model: $Y$…
Mark Borgerding
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How to remove reflections from images?

I've been playing around with making images better and removing all the unwanted disturbances from it. I found out a major concern would be removing the unwanted reflections that might come. I've gone through a paper that uses ICA to get rid of…
vini
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Audio EQ Cookbook without frequency warping

The famous https://www.w3.org/TR/audio-eq-cookbook/ offers a set of [real] biquad filter calculation formulas that generally work fine. However, when filter's frequency approaches Nyquist frequency the Q (bandwidth) specification of a filter becomes…
aleksv
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Group delay of the FIR filter

For an FIR filter, with symmetrical tap values $h[N-1-n]=h[n]$, why is the group delay $\frac{N-1}{2} T$ (where $N$ is the number of taps of the FIR filter and $T$ is the sampling time)? Why is linear phase so important for the filter response?
Jayesh Parmar
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How to smooth a signal?

The easiest way to smooth a signal is by moving window average. A more advanced way is to use a Savitzky-Golay filter. From wikipedia: The main advantage of this approach is that it tends to preserve features of the distribution such as relative…
Andy
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Questions about discrete signal energy calculation

I'm looking at the definition of signal energy (e.g. Wikipedia, cnx.org). For discrete signals, it's defined like the following, where $x(n)$ holds the signal: $ Energy = \sum_{n=-\infty}^{\infty} |x(n)|^2 $ So my questions: For a windowed,…
stackoverflowuser2010
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why Gaussian noise is usually used?

Gaussian noise with different SNR levels are usually used in research works to simulate a realistic environment. How can researchers guarantee that Gaussian noise can simulate the reality of a System?
SAH
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YIN Pitch detection Algortithm ( how do I improve my results )

I am using YIN algorithm in a school project of mine which uses pitch detection on guitar sound. I when I play a note I get random frequencies at the beginning until they stabilize. I am thinking those are probably from action of pick on the…
Ajit
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How to compute the main lobe width of generalized Hamming windows (i.e. Hann, Hamming, etc.)?

Is there a way to compute the main lobe width of windows of the generalized Hamming window family (i.e. Hann, Hamming, etc.)? By main lobe I mean the first zeros left and right of the center of the Fourier transform of the windows. I could not find…
koffer
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How do I evaluate the performance of a segmentation algorithm?

I'm currently on a project of liver tumor segmentation. I segmented the liver using region growing, and I have to assess how accurate the result is. I recently learnt that there are certain metrics for assessing the accuracy of the region growing…
Gomathi
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Time resolution of the Short Time Fourier Transform (STFT)

I'm struggling to figure out how the time points of an STFT are calculated, and I can't find a definitive answer. Let's say I have a 4Hz stationary signal and I'm going to use a 64 second window with 3 second overlap. So that's a 256 point window…
Alex Shaykevich
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