Questions tagged [pattern]

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Detecting expected patterns in repeated measurements

I am new to signal processing and I am trying to learn myself. To understand what i am interested in, let me show this on example (note that this is just a random example to illustrate). Here is some ...
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1answer
60 views

How do I create a polar plot from a multi-channel sound file?

I have a multi-channel sound file from a microphone array. I want to get the polar plot in Matlab in order to get the directivity patter of the sound source. How do I do this? I did the FFT on the ...
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41 views

What principles to use, in order to create field that will be read by OCR?

I currently have an invoice, where some numbers are written by hand, and I would need to read them automatically. My past experience is that people who write numbers will them write in so many ...
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17 views

How to generate the filter bank for a wavelet adapted to a pattern?

Some textbooks like Daubechies (1991) and Strang & Nguyen (1996) give algorithms to construct wavelets with specific properties. But, I am trying to construct a filter bank for a wavelet that is ...
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1answer
120 views

Detect Gradual Increase Before a Decrease in Noisy Data

I have data that'ss not too noisy and I am trying to detect a pattern where it gradually increases then decreases in a short period of time (20 ticks? it should be roughly similar per session but can ...
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2answers
37 views

Can amplitudes be used to differentiate one signal from another?

I have use case, where there are lot of sensors placed under ground.The sensors give amplitudes each second.So my aim is to detect if some anomalous activity takes place at that point. IF an activity ...
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44 views

Measure How Much Pattern Is Present In Signal

I have some pattern signal. This pattern signal will be played in noisy room. Then it will be recorded and processed. I need to show that my processing algorithm improves the signal. My idea is to ...
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18 views

match a pattern in a stream of bits

I feel my question is somewhat related to this, but I'm not sure how to do what I want. I get transmissions of ~1000 bits at a time, which may be corrupted by noise. To try and infer data from ...
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2answers
677 views

Identify random repetitive patterns

Forgive me if it’s too basic, I finish engineering a while ago. Given any time series, not periodic, I would like to find any repetitive pattern that is distinct (by some given measurement) and is ...
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41 views

Comparing two audio (Phone operator messages)

I have this two wavs. Same audible audio differente data. The audios are phone operator messages, so they are always the same. Wav:http://instaud.io/3Ezu Wav:http://instaud.io/3Ezw Using this ...
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1answer
162 views

How to programmatically find a sharp change in slope

First, apologies if I have the wrong group or this question is far too easy for this group. I am (as you'll see) a newbie. Please point me to another, more appropriate group OR tell me how to fix the ...
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1answer
26 views

detection of periodicities in n-dimensional signals

Generally speaking, what analyses are necessary and sufficient for the detection of periodicities in an n-dimensional signal amounting to a discretely sampled density distribution over n-dimensional ...
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2answers
504 views

Filling hatched areas in image

I'm trying to extract / fill the walls in a floor plan, the walls are filled with a (cross-)hatch pattern at a more or less fixed angle. I've managed to remove most of the "noise" by masking the DFT ...
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154 views

Pattern recognition

I am new to the world of computer vision, so please excuse my basic questions. I have two patterns: one consisting of a single circle of radius $r$, and one made of several circles, still of radius $...
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1answer
312 views

Pattern matching methods: Based on Area and Based on features

Good morning, I'm new to image processing and I'm currently working on a project for pattern matching and OCR more specifically. In the state of art I've found the matching process can be classified ...
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1answer
42 views

Can Binary Content alone affect Noise Performance?

Assume we got a transmitter and a receiver. We send a binary stream of let's say 8 bits (the stream length cannot change), using AM-modulation. We have no info on the channel/noise characteristics. ...
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1answer
92 views

Neural Network learning project based on 8 wave signals over 1 second at 1 sample every 10 ms ( hence 100Hz )

I'm currentely trying to train a neural network that can decide wether a pattern produced by the movement of a hand near capacitive sensors is as expected, or random. I have an MPR121 microchip linked ...
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1answer
58 views

Engine for Google / Browsers to detect manipulated images? [closed]

Would it be possible for Google and web browsers to scan images and detect doctored photos? For example, a web browser could check for abnormal color gradients and signals that indicate if a photo ...
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0answers
65 views

Determining periodic pattern when there is pattern which period is multiple of former

I have periodic signal, say, it has year period, yearly pattern. I want to check if also has quarterly pattern. Event if there is no visible quarterly pattern, Fourier Transform of this signal has ...
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1answer
45 views

Finding a change in a signal

I am looking to some C algorithm(for MCU), where I have these signals : First graph you can see that there is an event in the middle and it goes back to normal, second and third there is some event ...
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1answer
220 views

How to detect lines arranged in a visual pattern in an image?

I have a black and white image like this: Visually, there is a clear pattern of black lines evenly separated by somewhat thicker white lines. The problem I need to solve is to automatically detect ...
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1answer
832 views

Find a small image pattern in another similar image

I have this pattern in the first image which I want to find in the second image. However the two images are totally different so I just need to find the closest set of indices where these two images ...
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1answer
1k views

Why does this Moiré pattern look like this?

I was making some gifs of Mobius transformations in Matlab, and some strange patterns began to appear. I'm not sure if a deeper knowledge of the filetype/algorithm is needed to understand this ...
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2answers
113 views

Question regarding using cardinality in pattern recognition

So I've read this article for a project im working on: Ortiz-Cataln: Cardinality as a highly descriptive feature in myoelectric pattern recognition for decoding motor volition, Chalmers Uni, ...
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0answers
153 views

Feature recognition within a single song

I want to write an algorithm in C++ which is capable of identifying specific features within a single song, e. g. the sound of a drum which is played 100 times during 5 min. State of the project So ...
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2answers
6k views

Which image filter can be applied to remove gridded pattern from corrupt jpegs?

I have around 1,400 jpegs that have been corrupted somehow and have lost the backup images. They all seem to have the same gridded pattern of lines over each (i.e. the gridding does not shift from ...
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0answers
218 views

Cross Correlation shows peak at the same location every time

I have a signal which is taken from an accelerometer and I'm trying to match patterns between different windows of the signal by cross correlation. To do this I take different windows of the signal, ...
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2answers
255 views

Measure similarity between quantized grayscale images

I want to measure the similarity between quantized grayscale images (8 levels) that mostly depict organic patterns found in nature, say pigmentation patterns in animals (zebra pattern, leopard spots,.....
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53 views

How accurate is Wavelet packet decomposition for emg signals with frequencies from 10 to 40 Hz?

I have an electromyographic signal sampled at a frequency between 10 and 40 Hz in a time window of 300ms. Is wavelet packet decomposition adequate in order to perform features extraction for ...