Signal Processing Stack Exchange
Signal Processing Stack Exchange

Questions tagged [pattern]

32 questions
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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 phenomenon, but I thought that there could perhaps be a…
B H
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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 image to image. Here's what one of these images…
Stephen E
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How to detect the presence one- and two-dimensional patterns in distributions of spatial points?

I have many point patterns, and I want to detect those patterns that have points arranged in lines that may be curved, intersected or broken. For example, on the following picture, the upper left pattern is not interesting but other three patterns…
Vladislav Gladkikh
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4
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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 vary slightly between different sessions). This…
Ta946
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Engine for Google / Browsers to detect manipulated images?

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 has been retouched? Google could fingerprint photos…
LifeInTheTrees
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Remove watermark from video

Is there a process to remove a watermark ever present across all frames of a video? I was thinking that comparing frames and taking pairs poorly correlated, could give a clue about the watermark both share. Or perhaps merging or adding all the…
Leopoldo Sanczyk
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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 whole recording and I plotted the magnitude in dB…
JohnIL
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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 different ways (overlapping with field name etc.) that…
Igor
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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 unknown. For example given this : I would like to…
Curnelious
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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 $r$, placed in an array fashion. These two…
Frusciante89
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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. Our end-system is triggered whenever a certain…
koita_pisw_sou
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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 peaks on all frequencies which are multiples of…
George Sovetov
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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 at a certain point. Any of them can happen per…
Curnelious
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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 the first thing I did was to import my *.wav-file,…
h_uat
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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, sliding it on the signal and taking cross…
user3597574
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