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Questions tagged [preprocessing]

Preprocessing is a relative term that usually refers to simpler operations applied to improve the operation of a more complex algorithm.

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Upsampling and downsampling signals as a preprocessing step for a neural network

I have audio data acquired from a 4 channels sensors array. As a preprocessing step for a neural network, I want to beamform and focus on the sound source. For higher resolution in the beamforming ...
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Is sound the best way to transmit a signal under water?

Could sound be used in transmitting sound waves under water digitally? Could the sound then be converted by a repeater to transit by radio waves? What other ways can a signal be transmitted other than ...
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How to take inverse fft of windowed and callibrated fft data? [closed]

I have done windowing and fft on a signal but when I try to recover original raw signal ,I am unable to do it .Can anybody help me. How to take inverse fft of windowed and callibrated fft data? ...
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How do I know if my EEG signal need denoising?

I recently started working on sleep study. For my research I download sleep EEG data from physionet. The EEG data has 100 Hz sampling rate and was recorded from 2 bipolar EEG site. When I start the ...
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1answer
594 views

Frequency analysis to determine low-pass cut off frequency

I collected some data for a practical application, where the signal represents force data obtained from an impact of a punch against a force plate attached to a quasi-rigid rig (it moves once the ...
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Seismology - PPV / VDV from geophone waveform data

I'm using an inexpensive seismometer to try and measure the effects of local HGV traffic on buildings. The device is connected to a Raspberry PI that has a Cirrus Logic Audio Card. The signal is fed ...
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1answer
188 views

Subtracting DC Offset a Complex Signal?

If I take the magnitude of a complex signal, and then subtract the mean amplitude, I remove DC offset but lose the real and imaginary components. How can I properly subtract the DC offset of a complex ...
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3answers
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How to perform a Rubberband-Correction on spectroscopic data?

I basicaly understood how the Rubberband/Baseline-correction works. The given spectrum is divided into (N) ranges. The lowest points in every range are determined. The initial baseline is built out ...
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Calculating gyroscope data from accelerometer and attitude data

I am currently collecting accelerometer and attitude data using smartphone sensors. Data is collected at 100Hz over 2.5 seconds. Of which there are 250 accelerometer points and 250 points representing ...
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1answer
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Does waveform-based ASR with lowpass filtering preprocessing still require the assumption of FFT?

I read some recent papers about time-domain speech recognition, and wondering if it steers away from the stationary assumption of FFT. However, some preprocessing operations like pre-emphasis and low-...
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399 views

The essential pre-processing steps in speech signal analysis

My question is that for simulating a new scheme for speech emotion recognition (feature extraction and classification), what are the necessary pre-processing steps (I mean any kind of normalization ...
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1answer
130 views

correcting mirror ghosting effect

I have an application in which I have to process images taken through a mirror. The camera and mirror positions are fixed, and the object is always in the same position with respect to the mirror. The ...
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1answer
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How to design bandpass filter in python when centre frequency is greater than sampling frequency?

I implemented basic bandpass filter using Scipy resource. But how to implement the same when signal is centred at non-zero centre frequency with centre frequency > sampling frequency. I trying to ...
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For extracting the characteristics of the signal what minimum duration should be considered?

Being non signal processing student I have a limited understanding of concepts. I have a continuous periodic bearing faulty signal of 10 seconds duration sampled at 12 kHz. So I have 120,000 ...
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1answer
89 views

Separate key-related frequencies from audio signal

I have various samples of various instruments sound, and I'm trying to classify them using pyAudioAnalysis and various Machine Learning algorithms. The samples ...
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1answer
151 views

Artificial Neural Network Preprocessing in Real-Time Applications

I've come across an issue with my ANN when attempting to port my offline analysis to an online, real-time, application. I currently train my algorithm using an array of input data, number of ...
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2answers
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pre-emphasis with scaling?

I am working on speech synthesis with LPC and I originally implemented a pre-emphasis filter: ...
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4answers
306 views

Is this image good enough for OCR?

Hello I'm trying to ocr on a special image. I've done adaptive threshold , polartocartesian transformation. this is my original image this is adaptive threshold this is polartocartesian ...
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pre-processing to improve feature detector before tracking

I am trying to make tracking for soccer player, I need to detect features from this player and then estimate the distance difference of these pixels over number of frames. first I have to detect the ...
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2answers
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Preprocessing audio signal for neural network classification

I need to identify certain features of the audio signal recorded from microphone in stethoscope. These sounds are only samples i've found, but the final signal will be probably a bit noisier (maybe ...
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What is the difference between “preprocessing” and “normalization”?

I am currently writing my bachelors thesis about on-line handwriting recognition. In this context, there are different methods to make the input data more useful to classifiers / to make learning ...
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1answer
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What are the proper pre-processing steps to perform Independent Component Analysis?

What are the proper steps for preprocessing my waveforms in order to perform an independent component analysis (ICA) later? I understand the how, though further explanation of that doesn't hurt, but I'...
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select meaningful part out of a signal (for goertzel)

I have an on going input signal, most of the time with no activity. Once in a while there is an activity (oscillations in different freq). I need to take good 205 samples out of the signal. what i ...
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2answers
2k views

Effect of different downsampling rate on EEG signal

I have a raw EEG signal of length 2,50,000 samples. I band passed it from 0.05-10Hz (sampling frequency=500). Then I down sampled it at 20Hz. Now question is: What will be effect if I vary down ...
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what are best features [closed]

I am doing OCR for Kannada and English. What are the best features in image? Please also tell me some tools to perform OCR before implementing it as code (like Rapiedminer for machine learning).
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3answers
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Is it an excessive pre-processing step in image processing?

I wanted to consult with some experts whether or not this pre-processing step is excessive for what I'm trying to achieve. I am in a similar scenario as the author of the article, where I have many ...
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4answers
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Preprocessing to improve Harris corner tracking between video frames?

In our unmanned aerial vehicle grayscale video image stabilization application, we're having difficulty finding the "good" Harris corners in frame N+1 selected from frame N. The source of the ...
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2answers
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Should I consider rgb values of a pixel as one value?

I was reading this paper for a project work. We train on 1.6 million 32*32 color images that have been preprocessed by subtracting from each pixel its mean value over all images and then ...
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2answers
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Why do envelope extraction before pitch detection?

I am referring to this report on pitch estimation. The author does envelope extraction using Hilbert transform before applying AMDF. What is the advantage of doing that? Is speech a narrowband or ...
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1answer
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voice recognition vs speech recognition MFCC

I have a basic understanding of the acoustic preprocessing involved in speech recognition: divide the speech into frames, find the mel frequency cepstral coefficients of each frame, construct a ...
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1answer
374 views

MP3 Decoding Discrepancy

Is it possible for two different decoders to output two different sample results for the same MP3? I'm decoding an mp3 on Matlab and it produces two columns (presumably one for each channel). When I ...
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1answer
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What segmentation methods can be used for simple images?

As related to the project I am currently involved in, I have come to realize that one thing that might help is for me to 'segment' my image. To that end, I have shown a very simple example below. ...
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1answer
165 views

Find the relation between two noisy periodic signals of equal length

[Thank you, @leftaroundabout for your helpful comments to my related question. I'm trying to ask a less confusing question here.] $0\leq\phi\leq 2\pi$ is a parameter that theoretically describes a ...
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3answers
862 views

How should I pre-process a real valued signal in order to use Kay's estimator?

I have 100,000 samples of a signal $x[n]$ that was sampled at 20kHz. The data is vibration data from a rotating machine, and contains a significant spectral component related to the speed of the ...