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Questions tagged [detection]

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52 views

How to set sigmas and kernels for 3D-Laplacian of Gaussian filters to blob detection in Matlab?

I have written code according to a paper for Lung CT images, but its output wasn't correct. I think it is because of the setting of its parameters. The paper is about a multi-scale method using a ...
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1answer
78 views

2D CFAR detectors

Constant False Alarm Rate is an adaptive detector used to distinguish between true and false detections. There are many types of CFAR and the number of these detectors reaches 25 like (CA-CFAR, OS-...
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0answers
51 views

detecting specific words in images?OCR?

i'm not sure if this question belongs here or in stackoverflow but i feel like it belongs here as it is more about the approach than the code itself. i'm trying to write a program that searches in a ...
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1answer
27 views

Voice masking for removing voice and not birdsong

First the problem I'm tyring to solve: I'd like to find a way of removing any potential noise from audio files recorded in noisy environments where we are trying to record birdsong. This is for the ...
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2answers
663 views

How detect signal from noise?

I'm trying to detect when a signal is "on" from samples I have. Those samples come from a software defined radio, if that matters, and the signal i'm trying to detect is a WiFi signal. The problem is ...
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1answer
100 views

Pulse duration detection

I have a signal sequence where multiple pulses with different amplitude and duration may occur at random times. White noise is present as well. I was searching for a Matlab function which could detect ...
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1answer
350 views

Probability of False Alarm versus SNR

I'm currently testing the performance of an energy detector using two tests. One test involves finding the optimal threshold to achieve a probability of detection(Pd) of 0.9 and a probability of false ...
1
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1answer
177 views

Getting started with wavelet-based real-time anomaly detection for temporal signals using Python

I have an anomaly detection problem I wanted to consider addressing in software (python) with wavelets. I’m new to wavelets as well as the python’s spicy.signal wavelet package, let alone with the ...
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1answer
36 views

How to choose good features for my machine vision application? [closed]

I am trying to create an application (with OpenCV3) that can distinguish sidewalks from streets by a real-time camera that is embedded in a glass. I have 3 question about this project: Which features ...
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0answers
60 views

Realtime detection of a simple sound

I was wondering if there are any simple tools I could use to detect a particular sound in realtime (and of course ultimately take some action after that). This is a loop of the sound I want to ...
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1answer
279 views

finding frequency range and dominant frequency of a stored signal

I have sEMG signals, captured from commercially available device. the signals are stored in .tdms file format. i want to varify whether the captured signals are really sEMG (or simply EMG) signals or ...
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0answers
118 views

Unbiased estimation of square in presence of Gaussian noise

I have a single scalar observation, $y$, of a scalar parameter $x$ in presence of additive Gaussian noise. That is $y = x + n$ where $n$ is the Gaussian noise. The variance $n$ is known to be $\sigma^...
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0answers
84 views

How to compute Harmonic Key from FFT or PCM datas

I would like to develop a web tool to determine the harmonic key of an audio sound. With an analyse on client side only. Nowday WebAudioAPI provide an AnalyserNode with the getFloatFrequencyData() ...
2
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1answer
29 views

If I line in the sound from a video game console, can I detect when a sound is played?

The question is as the question is. It won't be this isolated sound though, it'll be a sound on top of background music. I think I can get a hold of the sound file itself from the data, but at worst I'...
4
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2answers
443 views

How to reliably detect the state (opened or closed) of sliding doors from a statically-positioned video stream

I have a mounted (static) camera that has a view of a set of sliding doors. Since doors are rectangular in nature, and they don't have many degrees of freedom, this seems like a problem that should ...
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2answers
623 views

Detect marker orientation inside an image

I've been reading how augmented reality works and how markers are detected. Anyway I can't find any resource that would help me in detecting an arbitrary complex image as, for instance, a book's cover....
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0answers
71 views

Another pitch detection problem

I'm a french student and I have to make a scientific project in group, so we decided to work on how automatically turn sheets music when a musician reaches the end of the page. For that I'm working on ...
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1answer
598 views

How to determine the symbol rate of a 2-FSK signal?

Let's say that I have a 2-FSK signal recorded so that the SNR is around 20 dB and the noise seems to be more or less white. The distance between tones is greater than the minimum distance needed for ...
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1answer
1k views

How do spectrum analyzers detect peaks?

Using peak search, I'm able to put the cursor on any of the several peaks on the spectrum analyzer display. I am trying to do something similar in software, with the output of the FFT of the radio ...
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1answer
442 views

What's wrong with this Average Magnitude Difference algorithm?

I implemented this Average Magnitude Difference algorithm in Javascript ...
-1
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1answer
160 views

Is image processing impacted by the lens or sensor size of the camera?

We want to configure a system for detecting and tracking basketball shots made. We have control over the cameras, so we can choose anything from a smartphone to a GoPro. Assume the scene is a typical ...
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1answer
71 views

Detection markers in images

I have a set of images with red, round labels on it. What I want is, to get pixel location of each of the label. One way, of course, would be to search for red color pixels. But the problem is, ...
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2answers
1k views

Envelope detector for non-zero mean signal (Matlab)

I used hilbert transform to get an envelope signal. envelope = abs(hilbert(inputSignal)) This works for zero-mean signal: But, for nonzero-mean case, ...
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3answers
170 views

Are radar resolution and detection capabilities not very tightly related?

Radar detection capacity is the capacity to determine the presence or absence of targets whereas the resolution is the capacity to identify two closely separated targets. If you can detect the target ...
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0answers
77 views

Detecting special points in signal

What tool/filter/mathematic operation would you use to detect the red points marked in this signal? As you can see there are several differentiated groups and I want to detect those moments in which ...
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0answers
82 views

Target detection for UAV landing

I would like to detect and track the following target to land an UAV. Target size is $1\rm m \times 1\rm m$. I have tried SIFT + FLANN but there is too few keypoints to have a good match. Have you ...
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0answers
293 views

How do we detect presence of background noise in audio?

The problem I am facing to solve is detect background hissing or humming sound in any audio stream. The audio stream can be of any type ranging from movies to talk shows. The background noise is ...
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0answers
239 views

Save ROI and background in two images

I'm using MATLAB Training Image Labeler app for labeling images and exporting the regions of interest (ROIs) which I save in .jpeg files.The ROIs are exported as a structure $1\times 430$ with two ...
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0answers
53 views

Annotate a dataset of images

I'll be recording a new dataset using a couple of sensors: kinect, stereovision cameras.. for a project for people detection using only depth information. But I don't know yet how can I annotate the ...
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0answers
730 views

detect what is noise in audio signal

I'm trying to filter noise from an audio signal. The signal was and is going to be recorded in a city environment which always contains some white/pink noise. At this moment I'm using two options to ...
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0answers
924 views

Epilepsy seizure detection in EEG

I want to develop a method to detect the occurrence of epilepsy seizure in an EEG signal. I am using a large data set for number of patients so the algorithm has to detect the seizure in any of the ...
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2answers
1k views

Object detection in binary image

This task comes from tracking object on a steady background. So far I was able to remove the background and obtain binary masks like this: I need to get bounding rectangle of the toy without the ...
0
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1answer
380 views

Audio Broadband Noise Detection

I have to quantify the broadband noise of an audio track. I've seen lots of things around and the only viable option to estimate the broadband noise (without having any information about it) is ...
1
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1answer
264 views

Best DSP algoritms for ultrasonic background noise cancellation

I am looking into detection of pressurized gas leaks by means of the broadband hissing sound (white noise) generated from pressurized leaking gas. The instrument will have a broadband microphone ...
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0answers
135 views

How to properly detect segments in a LCD segment display

I have been given the task to develop a code which checks if the display of a device is showing information correctly (i.e. any segments are activating when they are not supposed to). To meet this ...
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1answer
411 views

how to detect short pause in a speech with noise?

I would like to count the number of short pauses in a speech and know the duration of the pauses by loading the signal into Matlab but I am very new to Matlab. Can anyone help and give me some ideas ...
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0answers
97 views

Object localization down to the pixel

I am somewhat confused on the terminology used in Computer Vision. Suppose I wanted to detect (localize) an object (say, a human) in an image. However, a box around the human is not sufficient, what I ...
2
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2answers
268 views

Detecting Central Axis (petiole/rachis) of a Pinnated Palm

I'm new in StackExchange and I'd appreciate some help. I'm working in an algorithm for detecting "aguajes", a particular kind of palm. So far, I got good results using a texture feature extractor and ...
0
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0answers
316 views

detect pattern of noise / sound from pcm data

First of all, I'm very new to this field, I've never learnt anything related to sound processing. So I have a case that requires me to detect noise inside audio files (16bit 8khz mono wave file). ...
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1answer
70 views

Moravec, Harris noisy window

Harris and Stephens writes about the interest window of Moravec: "The response is noisy because the window is binary and rectangular", and suggests applying a Gaussian window. My Question: Why is the ...
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1answer
375 views

How does the PASCAL VOC challenge evaluate the task of object detection?

I fail to understand the evaluation parameters like true positive, false positive and false negative in detection and classification tasks. can anyone help me to figure out what does each of these ...
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1answer
150 views

Computer vision, Coupon code detection, sugested algorithms

The telecommunication operator in my country has coupons that used to recharge the balance I want to develop an Android application, that with the camera can take the scratched number and recognize ...
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0answers
104 views

Probability of Detection and pulse-pulse decorrelation time

I'm trying to analyze the probability of detection ($P_d$) for a Swerling II target. I know that the Swerling II target assumes that the Radar Cross Section (RCS) is an exponential probability density ...
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0answers
406 views

Correlation between two graphs in Matlab

I am trying to make a system that detects footsteps. First I filter and decimate the original signal, then I make a convolution between the filtered signal and a single footstep, then I extract the ...
3
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2answers
227 views

Key detection Dance Music inaccuracies - matlab

I have been working on a project with a vide variety of functions for DJ'ing. I am nearing the end, however, the accuracy rate on the key detection part of it is not pleasant when fed tracks of Dance ...
2
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1answer
999 views

Efficient Marker Detection for Images

I need to detect a known number of simple markers (chessboard patterns) in a color image efficiently. I implemented normalized cross correlation (NCC) as a pixel shader via WebGL since I need this to ...
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1answer
1k views

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 ...
0
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1answer
296 views

Stopping Viola Jones Face Detection early

I want to try to improve an image processing technique for finding faces in images. I want to stop the Viola Jones face detector before it finds all faces, and do histogram equalization and other ...
2
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0answers
3k views

Why is LBP generaly faster than HAAR?

I am digging into Haar like and LBP features. More precisely its implementation in OpenCV. Every article or forum entry I found states, that LBP is faster than Haar. My local tests also confirm this ...
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3answers
1k views

How to classify accelerometer data?

I am trying to detect if a car did accelerate or did brake by using the accelerometer of the iPhone. In the figure below I plotted the collected data. (To collect the data the phone was laying flat ...