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Questions tagged [downsampling]

231 questions
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Which pcl filter to use to downsample a point cloud

I am getting a point cloud from a lidar on an autonomous driving robot, but it's too much data to process. I already implemented a passthrough filter. I did get a very good result and I was asking myself if there were others filters or methods I…
tony497
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Need example to downsample plots with Bokeh

I'm relatively new on Python and Bokeh technology. My goal is actually to be able to display line charts containing millions of points (like around 5 millions) in a browser. I'm conscient that actual browsers can't handle such an amount of data.…
Alexandre D.
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Downsampling data in Matlab by averaging

I have 2 data sets in Matlab that I need to plot against one another - one on the xaxis and one on the yaxis. The data for each set was collected using a different method so the sampling rate is significantly different and until I don't the same…
Maheen Siddiqui
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Reducing moire when downsampling halftone comic images

How can I reduce moire effects when downsampling halftone comic book images during live zoom on an iPhone or iPad? I am writing a comic book viewer. It would be nice to provide higher resolution images and allow the user to zoom in while reading…
drawnonward
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Perceptual Image Downsampling

So here is my problem: I have an image, that image is large (high resolution) and it needs to be small (much lower resolution). So I do the naive thing (kill every other pixel) and the result looks poor. So I try to do something more intelligent…
tzenes
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Python Image Library: clean Downsampling

I've been having trouble trying to get PIL to nicely downsample images. The goal, in this case, is for my website to automagically downsample->cache the original image file whenever a different size is required, thus removing the pain of maintaining…
Li Haoyi
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Lanczos Interpolation in Python with 2D images

I try to rescale 2D images (greyscale). The image size is 256x256 and the desired output is 224x224. The pixel values range from 0 to 1300. I tried 2 approaches to rescale them with Lanczos Interpolation: First using PIL Image: import numpy as…
tamtam_
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How to downsample a signal preserving spikes?

I'm analyzing a signal sampled at 200Hz for 6-8 seconds, and the important part are the spikes, that lasts 1 second at max. Think for example to an earthquake... I have to downsample the signal by a factor 2. I tried: from scipy import…
Marco Sulla
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Downsampling signal from 100.21 Hz to 8 Hz (non-integer decimation factor)

I have found the following method to downsample a signal in python. I would like to use this method with a sample_rate of 100.21 but I think currently it only works for integer powers of two. Is there a possibility to downsample my signal with…
machinery
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Sample to Create Uniform Distribution from Non-Uniform Data

Given a dataset with a non-uniform distribution (highly peaked) I want to resample to create a new dataset with an approximately uniform distribution. My approach: Divide the data into bins. Target bin level = Smallest number of samples per bin,…
Ron Cohen
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Is it possible to render to texture's mipmap level 1 while sampling from level 0? (opengl, texture 2d)

Is it possible to render to one of RenderTexture's mipmap level while sampling from other levels? The situation is i want to downscale a texture 4 times using shader, i could put all these intermediate results together on a big texture (at level 0,…
21k
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Optimizing the code for downsampling

I have a table like this, which is flyTracesFiltered. Time Right Left 1 0.000000000 18.21980 30.98789 2 0.009222031 22.15157 37.18590 3 0.022511959 25.63218 42.49231 4 0.029854059 28.43851 46.57811 5 0.039320946 30.43885 49.29414 6…
chiser
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Web audio API downsample 44.1 khz in Javascript

I'm using RecorderJS to record a microphone stream from the user. The default export is a WAV file at 44.1 kHz, 16bit. Is there anyway I can downsample this to 11kHz or 16kHz without it sounding weird? Is there anyway I can get a 16bit 16khz WAV…
tehmaestro
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How to downsample values in array?

I have an array of length 4096 It contains the results of the calculated FFT. Results should be displayed on a window length of 1024 How to reduce the value from 4096 to 1024 and that the results remain correct. Is this a good way? int index =…
Avokado
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Misconceptions about the Shannon-Nyquist theorem

I am a student working with time-series data which we feed into a neural network for classification (my task is to build and train this NN). We're told to use a band-pass filter of 10 Hz to 150 Hz since anything outside that is not…
AnneH
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