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Questions tagged [downsampling]

231 questions
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image downsampling with an exact integer factor

I have a very basic question about image downsampling. If I have an image that is of size 256 times 256 and I want to reduce it to size 128 times 128, is it completely safe to now take every alternate pixels? I am assuming that the new sampling…
Luca
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How to down sample data keeping the same frequency distribution of one column

I am trying to down sample a data set and keep the same frequency distribution as one of the column. The approach is 1) determine the baseline frequency distribution, 2) use the baseline frequency distribution to sample the row range, 3) use the…
user974465
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Getting a complete white image on downsampling

I performed an image downsampling with averaging operation. The image is divided into 2 by 2 blocks, then it is downsampled by 4 times. New pixel values of the downsampled image are replaced with the mean of each block as follows: img =…
Celine
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The minimum value of inSampleSize for loading a large bitmap

After searching SO and reading lots of answers I wrote the following code to get the minimum value of inSampleSize for downsampling a large bitmap: public Bitmap load(Context context, String image_url) throws Exception { BitmapFactory.Options…
user1922137
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Downsampling cell array elements, Matlab

Given a cell array of n elements (n > 1), each element being a 2-d array with x=k number of rows and y columns (variable across cell elements), what would be the best way to down-sample each cell element by randomly removing samples in the y-dim to…
Japonica-osaka
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Summarising a POSIX (date/time) referenced vector in another date/time referenced vector

Hi all R efficiency gurus (and people with a similar question to me), This is an efficiency question. I have some very large data set. One data.frame contains data from one instrument with a POSIX date and time with values at a very high frequency.…
userX
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How to downsample image with custom kernel in opencv?

I want to down sample image, but i don't want to use gaussian kernel. Is there any opencv function for that purpose? UPDATE:i have an image with size m by n. i want result image with size m/2 by n/2, such that: result[i,j]=( a*input[i*2,j*2]+ …
fyo
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How to trim PCM data to identify sample count or frame count to feed?

I want to feed libsamplerate (a library to downsample audio data which needs the following struct filled: typedef struct { float *data_in, *data_out ; long input_frames, output_frames ; long input_frames_used, output_frames_gen…
frankish
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Pandas Downsampling Issue

I have a csv file with two columns containing dates and 0 or 1 like so: 17/08/2012 07:47:16 0 17/08/2012 07:54:31 1 17/08/2012 08:02:31 0 17/08/2012 09:22:33 0 17/08/2012 09:58:05 0 17/08/2012 12:26:59 1 17/08/2012 20:56:00 0 18/08/2012 10:04:06…
luckyfool
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Downsampling pcm/wav audio from 22khz to 8khz

My android application needs to convert PCM(22khz) to AMR , but the API AmrInputStream only supports with pcm of 8khz. How can i downsample the pcm from 22 khz to 8 khz?
Raneez Ahmed
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Downsample a wave file

I need to downsample a 16000 hz PCM 16 bit wave file to 8000 hz. I dont have much knowledge(almost no) on audio processing, i just understand bits, bytes, shifting etc as all programmers understand. It is a Windows Phone application. What do you…
mehmet6parmak
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VOIP SIP - Help to encode from PCM to U-law

I’m working to VOIP Windows Phone project (Soft-phone application for Windows Phone). At the present, I (Windows phone soft-phone) can receive and heard voice of another soft-phone, only ONE-WAY. I can send my voice (RTP packets) to another…
hthoang88
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Timeseries denoising and downsampling

What are some different denoising techniques for time series? What conditions have to be in place to downsample a time series without loss of information?
user11715878
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averaging each two image in 10000 images array in python

I am new in python. I wonder if you can give me an idea on how I can average each successive two images array in matrix of 10000 images. I want to down sample the cadence of my film. I found the following code, but I want to average a matrix of…
Souchan
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randomly sampling of dataset to decrease the values in the dataset

I am currently trying to decrease the values in a column randomly according to a given sum. For example, if the main data is like this; ID Value 1 4 2 10 3 16 after running the code the sum of Value should be 10 and this need to be done…
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