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1500 questions
7
votes
3 answers
count blood cells
How to count blood cells in opencv? The problem is that they stick together.
The example picture :
Maybe pairwise geometric histogram (Geometric Histograms) suitable for matching partial circle shape?
mrgloom
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7
votes
1 answer
Abs(poles) < 1 by what margin for a stable filter?
I checked the literature for recent algorithms used to design a digital filter that is a minimax approximation of a desired frequency response. All the articles I found work out examples where all the poles have magnitude less than 0.92, or less…
Ted Ersek
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7
votes
3 answers
Acoustic Scenarios With Negative SNR
For all the practicing engineers out there:
Where have you encountered a negative SNR?
How negative, in dB, was it or estimated to be?
Where would you expect to encounter a negative SNR?
Note: I am also counting interference signals as noise,…
The Dude
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7
votes
2 answers
Explaining / Communicating spectra: Generating Visualizations
I'm very often in the situation that I need to explain / visualize spectrum of signals or frequency behaviour of systems (esp. filters). My favourite, very "textbook" styled way of communicating these would be, in simpler cases:
¹
Typically, I'd…
Marcus Müller
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7
votes
2 answers
Why does diagonal loading of a covariance matrix make an adaptive beamformer more robust in the case of a perturbed array?
It has been shown that 'diagonal loading' a covariance matrix derived for an adaptive beamformer can improve robustness of the beamformer when the antenna array is perturbed, albeit at the expense of background noise power.
The question is why does…
Spacey
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7
votes
5 answers
What Is the Difference Between the Terms Color Intensity and Color Saturation?
In Digital Image Processing, what is the difference between the intensity and the saturation of a color?
How would you explain the difference to a newbie?
Solace
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7
votes
3 answers
Maximum Likelihood for Colored Noise
I have the following question about the maximum likelihood (ML) in presence of inter-symbol interference and colored noise.
Assume the communication system is as follows. Information source, modulator, transmit pulse filtering, channel, AWGN,…
Noor
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7
votes
1 answer
Is an image a random variable or a random process?
Is an image a random variable, where each pixel is a realization of the same random variable? Or is an image a collection of random variables (if an image is of size mxn, there are mxn distinct random variables)?
In the latter case, are the RVs…
Sam
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7
votes
1 answer
How to change volume of a PCM 16 bit signed audio?
I know I can multiply samples, then clip but perceived volume is non-linear for humans.
Can you please help with a formula.
apocalypse
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7
votes
1 answer
Variant of discrete fourier transform that isolates phase delay?
I'm not quite sure of the mathematical terminology here but...
Is there a variant (or post-processing) of a Discrete Fourier Transform that separates the shape of a signal from any phase shift applied to the whole signal?
For example this…
finnw
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7
votes
1 answer
How to choose a windowing function when performing a Chirp $\mathcal Z$-transform?
I've got some data sampled at 32 Hz. The only interesting stuff is happening between about 0-8 Hz and I've got to do real time batch processing and detect events with a delay of no more than a second. So that means I can only perform FFTs with 32…
Ashutosh
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7
votes
2 answers
Phase-shift filter design
If a time-domain signal has sharp corners, its frequency spectrum will contain high-frequency components. Truncating the spectrum results in Gibbs' phenomenon. So if you're trying to design an FIR, you really want the target frequency response to be…
MathematicalOrchid
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7
votes
1 answer
How does google map put together satellite pictures?
Just out of curiousity, does anyone know how does google map put together all those massive quantity of satellite pictures with with high accuracy? What advanced computer science technology has it employed?
carl
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7
votes
4 answers
Does taking the Hilbert transform extract the envelope of audio signals?
I want to extract the envelope of music signals with a sample rate of 44.1kHz.
I used the MATLAB command: abs(hilbert(mysignals)), but the resulting signal is similar to the original signal, not the envelope.
Does taking the Hilbert transform…
Linda
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7
votes
1 answer
importance of using histogram equalization
I'm reading opencv tutorials and I'm diving into histogram equalization. i have looked in wikipedia, there is a nice example that sums up exactly the problem:
original:
equalized:
but for getting this result i would take a different approach:…
nkint
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