Questions tagged [interpolation]

Interpolation is a method of constructing new data points within the range of a discrete set of known data points.

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Calculate interbeat intervals

I'm currently reading a paper and I can't seem to make sense of a certain part. A link to the paper: removed The part I don't quite get is on page 286 (after the part where they explain their filters)...
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1answer
3k views

Interpolation in Contrast Limited Adaptive Histogram Equalization

I have been trying to implement the CLAHE algorithm and came across this page which states step by step procedure for the algorithm. I understand the initial steps to perform HE of tiles in the image....
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2answers
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Fitting piecewise splines to noisy data

I have a system that gives me a noisy data set similar to the one generated by this matlab/octave code. The y-axis represents the signal intensity and the x-axis represents spatial distance. ...
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2answers
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How does subpixel image shifting using DFT really work?

I am trying to assess the quality of several image interpolation methods for an application that involves generating subpixel-shifted images. I thought I could compare the results of a subpixel shift ...
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3answers
934 views

creating a seamless signal / loop using interpolation

I'm trying to create a seamless loop using a "non-periodic" signal using interpolation to smooth out the beginning and the end but I'm still getting a click at the beginning when it loops and I listen ...
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1answer
550 views

How to mix two signals without changing the overall loudness?

I have two audio signals that I want to mix at various mixing ratios. Initially, I simply went for something like $y(t) = \alpha \cdot x_1(t) + (1-\alpha) \cdot x_2(t)$ where $\alpha$ is the ratio ...
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4answers
16k views

Interpolation with an FIR filter

How can I use interpolation with an FIR filter? I am more familiar with interpolation such as nearest distance interpolation, linear interpolation and so on. Suppose a signal is given as the ...
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4answers
8k views

How Can I Resample a Signal with an Arbitrary Factor (For Example - 128000Hz to 16000.1Hz) in MATLAB?

I need to simulate the sampling of a continuous (fsCtu = 128000Hz), acoustic signal with two microphones that have a slight offset in sampling rate (fsMic1 = 16000, fsMic2 = 16000.1) in Matlab. What ...
13
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2answers
2k views

Real-valued ringing when zero-padding odd-length FFT

So I'm trying to write a frequency-domain interpolator that zero-pads the frequency response of a signal and inverse transforms. There's two cases I have to deal with: Even-length response - have to ...
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2answers
5k views

Time domain interpolation using FFT with zero padding on the end

I've got a situation where I'd like to use an FFT to do interpolation in time on some complex data (I need to go to the frequency domain anyways to window my data). The notional way of doing this ...
4
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1answer
1k views

How can I smoothly interpolate between 2 position?

I've got a 1D signal (position of a servo motor over time) and I've extracted 'peaks'/'key' positions picking running average "local extrema" points. Below is are 2 plots from 2 servos and the white ...
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2answers
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How to prevent “zipping” effect on a modulated fractional audio delay line? (Flanger)

I am implementing a Flanger using a fractional delay line. I am modulating the length of the delay line using a sin function. The delay line already uses linear interpolation to compute the delay ...
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1answer
415 views

How do I numerically calculate a function from its noisy gradient?

I have the model $\ s(x,y)=x^2+y^2, 0 \leq x \leq 1, 0 \leq y \leq 1 $. Instead of observing the model directly I am observing the derivatives of the model + some noise (e): $\ p(x,y)=s_x+e, q(x,y)=...
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1answer
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Plotting DNA chromatogram trace data

Sanger DNA sequencing produces a chromatogram trace which can be visualized with a number of programs, including FinchTV or ChromasLite. The raw data consists of co-ordinates for each of the four DNA ...
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1answer
3k views

Interpolation of a gray scale image in matlab [closed]

I want to fill the black areas with the value of neighboring pixels. Kind of interpolation. Can any one suggest me how Can I do in matlab.
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1answer
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FFT, interpolation and phases

I am trying to understand how to interpolate discrete sinusoidal data that I (for now) generate myself, and I get problems that I don't understand. I'm a newbie in this field so do not hesitate to ...
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3answers
1k views

Sense of zeropadding in a time domain

I have the task related to Radon transform which contains a subtask which uses resampling by means of DFT. Let's consider the non-periodical discretized signal (Fig.1) (for example the string of ...
10
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1answer
768 views

How can I automatically classify peaks of signals measured at different positions?

I have microphones measuring sound over time at many different positions in space. The sounds being recorded all originate from the same position in space but due to the different paths from the ...
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2answers
6k views

Differences between filtering and polynomial regression smoothing?

What are the differences between classical low-pass filtering (with an IIR or FIR), and "smoothing" by localized Nth degree polynomial regression and/or interpolation (in the case of upsampling), ...
9
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1answer
4k views

How do I use a Savitzky Golay filter to find local maxima (in between samples) in a discretely sampled 1D signal?

I have a seismic signal y(i): Here I have found one maximum: i=152.54, y=222.29 manually and plotted it in red. I want to find all maxima automatically. I read that the Savitzky Golay Filter (SGF) ...
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2answers
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Finding local peaks in-between samples

I have $n$ discrete samples of a seismic signal $y[n]$: I want to find local maxima in the signal. A naive test for if $y[n]$ is a maximum would be: $$y[n]: maxima \textbf{ if } y[n] > y[n-1] \...
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1answer
547 views

What interpolation methods can I use to get the tightest fit for these curves?

I am working with MRI images of the brain that have certain areas marked by hand like and . I am trying to come up with an interpolating function that will let me describe such curves so that I can ...
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2answers
6k views

Frequency-domain zero padding - special treatment of X[N/2]

Suppose we wish to interpolate a periodic signal with an even number of samples (e.g. N=8) by zero-padding in the frequency domain. Let the DFT X=[A,B,C,D,E,F,G,H] ...
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6answers
2k views

Calculating the PDF of a waveform from its samples

A while ago I was trying different ways to draw digital waveforms, and one of the things I tried was, instead of the standard silhouette of the amplitude envelope, to display it more like an ...
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2answers
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How can I design Nyquist interpolation filters with the Parks-McClellan algorithm?

We can easily design interpolation filters that obey certain frequency-domain constraints using the Parks-McClellan algorithm. However, it's not immediately clear how to enforce time-domain ...

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