Signal Processing Stack Exchange
Signal Processing Stack Exchange

Questions tagged [compression]

This is for reducing the amount of data required to store a signal, whether lossy or lossless.

https://en.wikipedia.org/wiki/Data_compression

114 questions
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How does adaptive Huffman coding work?

Huffman coding is a widely used method of entropy coding used for data compression. It assumes that we have complete knowledge of a signal's statistics. However, there are versions of Huffman coding that are used with streaming media and cannot…
Phonon
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Huffman coding of a non-dyadic probability distribution

Wikipedia: Huffman coding is optimal among all methods in any case where each input symbol is a known independent and identically distributed random variable having a probability that is dyadic. Prefix codes, and thus Huffman coding, in particular,…
Gideon Genadi Kogan
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What is the relationship between image entropy and LZMA compression?

I've got some pictures which i want to compress by using LZMA algorithm in Python. I'm using this implementation. I've tried to measure the entropy of an image by using skimage.measure.shannon_entropy entropy =…
Francesco Binucci
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A non-lossy aka lossless codec without patent-restrictions for audio?

The term non-lossy codec means the coding thing having no compression lost, more here. I need such format to process the audio, without destroying the quality. Wikipedia mentions in the context of lossy compression: Ogg Vorbis (noted for its lack of…
user258
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4 answers

Discrete Cosine Transform

Is this piece of text (written by me) true about Discrete Cosine Transform ? Discrete Cosine Transform (DCT) is a lossy data compression algorithm that is used in many compressed image and video formats, including JPEG, MJPEG, DV and MPEG. In this…
Suvi
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Compressing plotted data with variable sample rate?

I'm currently plotting high sample rate data by down-sampling by a factor and averaging. Most of the time this is working ok, but I am aware that at very low zoom levels (zoomed right out) the averaging is hiding vast amounts of data. I have a…
Tim
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Sampling from a distribution with arithmetic coding

I'm struggling to implement a sampling scheme where arithmetic decoding is used to generate the samples. This is based on excercise 6.3 from David MacKay's book, where you compare rejection sampling with arithmetic decoding sampling. For each…
Tom Kealy
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How is this Huffman tree converted into electric voltages?

This is the Huffman tree for word "stackexchange": How is this Huffman tree converted into electric voltages?
Sammy Matt
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Karhunen-Loeve Matlab code

I am trying to learn about KL Transform. I found this code. I am struggling to understand how does [v{m},d{m}]=eig(img_covariance); differ from [v2,d2]=eig(img_covariance);, The former returns two matrices of eigenvectors, from which the second…
Suvi
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Are there hardware solutions for general purpose data compression (e.g. zip)?

Are there hardware solutions to compress data? Specifically, I am looking for a low power IC that implements something like zip compression, to take load off the microcontroller, as it often is very resource constrained. For example, doing online…
freejuices
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Math for converting downward compressor to upward expander

I’m looking to make an upward compressor. Could it be as simple as making the compressor ratio a negative number OR making the numerator less than 1?
tjcinnamon
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What does the word Entropy refer to in Entropy encoding

I have come know of Huffman and Arithmatic encoding that try to curtail redundant data and thus compress data. Why are they called Entropy encoding? What does that mean? Why not just call them compression encoding?
quantum231
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Signal quality metric

I have floating point data signal. I apply lossy control to it and I need some kind of metric to determine its quality. In image processing, there is PSNR (or MSE). I tried to use the same for it, It gives me some kind of result. But is there…
Martin Perry
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using Huffman coding to understand an daily incident

Yesterday, I went hiking with friends who are all studying the same electronic engineering degree with me. During the hike, we talked about female classmates within our degree. Since there are only few female classmates within our degree, I only…
galoischan
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Arithmetic coding of images

How does arithmetic coding work with images? I understand how it works with textual messages but I don't understand how it works with images. So with textual data, we use the probabilities of the symbols to divide the interval between 0 and 1 into…
Suvi
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