Signal Processing Stack Exchange
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How can I detect elements of GUI using opencv?

Given a screenshot of an application, is there any way of finding GUI elements of that application using only opencv? (something like in the image) I tried to play with blending the image and other effects from the coherence.py sample in the opencv…
Radu Enea
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Ultrasonic signal detection

I have created a fairly simple TDOA system that uses ultrasonic signals emitted from two speakers to geolocate (relative to the speakers) mobile phones. The two signals are separated by frequency. The system has the following constraints: The…
Jim Clay
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Optimized ANSI C libraries for DSP

I am new to DSP. Are there good open source ANSI C implementations of DSP algorithms? MATLAB is great at prototyping but once we move to coding in C, it takes time and we end up making too many mistakes. I would guess there must be good repositories…
Ktuncer
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Detecting changes between voice and music

I have a bunch of audio files that have both speech and music parts (think radio). For instance, a given file might consist of the following sections: music --- speech --- music --- speech --- music --- speech --- music My goal is to detect when…
haroba
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How to measure the quality (or difference in quality) of different images?

I would like to measure the quality of a color image, possibly as a difference to another image, but if possible, on its own too. This question comes from the fact that we have a vision application, and improve lighting conditions, calbirations, and…
Geerten
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SPL values from FFT of microphone signal

I am trying to get a frequency response vs dB SPL plot for recorded sounds. I have a microphone with a flat response, a sensitivity of 4mV/Pa, and 1 Pa = 94dB. To get the dB SPL, I have the following formula: $dB SPL = 94 + 20 \cdot…
hackyday
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How can I detect buttons in a GUI of an app with pattern detection using python?

I will explain taking as example the GUI of the Calculator app in windows. Given this Calculator application open and focused, I need to find a way of detecting all the buttons.I can only use non-intrusive methods, so things like button id are out…
Radu Enea
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How to analyze audio input/spectrum correctly

I am quite new to Java and Signal Processing, but I was assigned a project dealing in audio processing. My topic given to me is a game that has a component of analyzing a song (any given song) and outputs data depending on the frequency currently…
user3241507
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MOD-N Circular Convolution

How to find MOD-2 Circular convolution for the two sequences $h =[-1,3,-2,1]$ and $x = [1,-1,-2,1,3,2,1,2]$. I know the answer is $7$ $0$ from matlab but I don't know how to find it graphicly or mathematically
saleh khalaf
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Why is mutual information symmetric but conditional entropy isn't?

Conditional entropy $H(X|Y)$ tells us how much the average uncertainty about a channel input $X$ is after observing channel output $Y$, and mutual information $I(X,Y)$ measures how much information about channel input $X$ can be obtained observing…
Dina Khaled
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In computer stereo vision, what does it mean to "look in"?

In trying to understand this answer to my earlier question, can someone explain why it is important that the cameras are not in the same plane when the focal distance is large compared to the separation between the cameras and the object? What is…
Stephen
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Derivative calculation

I have a series of data (single array). If I take this data and plot it, I can see that there are multiple peaks. However If I zoom in to a section of data, I see that there is substantial noise. I like to detect how many peaks in the data using…
Ktuncer
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What's the similarities and differences between Wigner transform and wavelet transform?

Wigner transform and continuous wavelet transform are both some kind of time-frequency representation of a signal. What are the similarities and differences between them? Could you give some comparison between them? Let's restrict ourselves in 1D…
xslittlegrass
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Can anyone explain me this MDFT polyphase filter bank?

I found a very interesting piece of code for MDFT polyphase filter bank here. Unfortunately, there doesn't seem to be a paper describing the theory. Does anyone know some reference for the code? I'm especially interested in these 3 topics: What are…
Pascal
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Extremely computationally intensive image/video compression schemes which offer better compression than industry standard JPEG/H.264

I am trying to search for image/video compression schemes which offer superior compression performance (holding image quality as constant) when compared to widely adopted industry standards (i.e. JPEG/H.264), but for reasons of them being either too…
Ang Zhi Ping
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