Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [data-compression]

The tag has no usage guidance.

0
votes
0answers
29 views

An interesting compression algorithm idea

I stumbled on this paper about compressing images using a kind of odd, but interesting idea. It seems pretty easy to implement and I was wondering if there is something wrong with it that I haven't ...
0
votes
1answer
36 views

Coding for data compression with large target's symbol set (where the target symbol set is larger than the source symbol set)

For data compression, every codding that I've seen is binary. It means we convert a language with $N$ symbol size to a language with $M=2$ symbol size. For example, in Huffman coding, the goal is to ...
4
votes
1answer
648 views

How does a predictive coding aid in lossless compression?

I'm working on this lab where we need to apply a lossless predictive coding to an image before compressing it (with Huffman, or some other lossless compression algorithm). From the example seen ...
0
votes
1answer
42 views

Is it possible to achieve greater than perfect compression using machine learning and big data?

Imagine Google wanted to make their chrome browser faster. Let "database" be all the machines which serve content from Google's servers, including Search and Google cloud services. Google begins using ...
3
votes
3answers
903 views

Algorithm to convert a fixed-length string to the smallest possible collision-free representation?

I have a US-based telephone number (in the format 000-000-0000) and need to convert it to a "shorter" representation. Using base32/64 produces too long of a string. I've discovered CRC-16, which ...
1
vote
0answers
33 views

Computing (near) optimal displacement tables

Suppose we have a two-dimensional table $T$ with $r$ rows and $c$ columns that is sparse. Let $T[i][j]$ be the element at the $i$th row and $j$th column of $T$, with zero-based indexing. We can ...
34
votes
6answers
7k views

Do lossless compression algorithms reduce entropy?

According to Wikipedia: Shannon's entropy measures the information contained in a message as opposed to the portion of the message that is determined (or predictable). Examples of the latter ...
2
votes
1answer
31 views

Is there an algorithm to achieve optimal compression in a “streamed” manner, assuming equal probability of each possibility?

(Sorry for the question title; edits are welcome.) Let's say that you have a set of data made of repeating units, consisting of a value with $2$ possibilities, a value with $3$ possibilities, $5$ ...
2
votes
1answer
32 views

what is a shearlet/shearlet transform and how can i use it?

from what wikipedia says shearlet is a successor to wavelets(whatever that is) and that they are extremely good at representing complicated data efficiently. But neither wikipedia nor other articles ...
0
votes
3answers
172 views

I think you can always compress compressed data, is it true?

In compressed data, repetition of same pattern is not a lot, so, you can expect it to be with space inside to contain always. I found a way to compress data without limitation. Is it right? Am I ...
2
votes
1answer
91 views

What is the best way to compress a string with only numbers and commas in it?

I have a string like this: 11,512,64,23,46,12,67,85,84 And I'm sure it's following these rules below: Only , and ...
2
votes
1answer
55 views

Compression algorithms for small strings - building upon / extending Huffman

I'm exploring algorithms to compress small strings like the following - every line is to be compressed individually, i.e. even those small strings should get compressed: ...
16
votes
4answers
5k views

Can data be compressed to size smaller than Shannon data compression limit?

I was reading about data compression algorithms and the theoretical limit for data compression. Recently I encountered a compression method called "Combinatorial Entropy Encoding", the main idea of ...
0
votes
1answer
75 views

What is the most compact (space efficient) method of storing an array of distinct integers?

I have an array of distinct integers which I want to save in the most compact manner. I may have to do occasional lookups, deletions, and insertions in this array so the compression algorithm must ...
5
votes
1answer
126 views

Most space-efficient lossy dictionary?

Short version: What is the most space-efficient lossy dictionary (with given false positive and false negative rates)? Long version: A lossy dictionary is a data structure $D$ that encodes a set $S$ ...
0
votes
0answers
17 views

Is reinforcement learning the right tool for inferring graph structure from sequence?

Sorry that this is a complicated question - I will try to get to the essence of it. I am interested in learning the structure of sequences of numbers in terms of a graph encoding specific types of ...
2
votes
1answer
48 views

Algorithm for estimating lossless compression factor

Is there any algorithm for estimating how well certain array of bytes could be compressed in lossless manner? Usage for me is to automatically choose "best" data reorder method without knowing what ...
2
votes
2answers
68 views

Does this progressive image compression exists?

I want to know if this progressive image compression that I have in mind exists and it it does I want know its name and/or get some references about it. The algorithm consists of converting one high ...
-3
votes
1answer
28 views

Character in Huffman encoding [closed]

Is a full stop regarded as a character along or must it be with a space in huffman encoding. I know of taking a comma with a space to a character.
1
vote
1answer
29 views

Compression with random dictionary

Is the following scenario theoretically possible, or provably impossible? Alice generates a 1 GiB file with random bits and sends it to Bob. This file is a shared dictionary they call Q. Now, Alice ...
1
vote
0answers
20 views

Attribute Selection for minimum number of clusters

I have a table consisting of some headers $P, Q, R, S$ (shown in blue in Table 1). According to the headers, the column $T$ is populated using some predefined logic. Now, any of the headers $P,Q,R,S$ ...
0
votes
2answers
48 views

Data compression with Turing Machine

For traditional algorithms compressed data may vary, while decompression algorithm is always the same. Are there any approaches, when (de)compression algorithm is also changing to provide best ...
0
votes
0answers
26 views

How much data can be send in 1 minute of audio with Smartphone speakers / microphones?

Having the current news about Google Assistant in mind, I thought that robots might use interfaces designed for humans to send data. Like a telephone interface. Then I wondered: What is the maximum ...
0
votes
0answers
45 views

What algorithm is most suitable for large text compression?

Currently, I am looking for an lossless compression algorithm that is suitable for a large amount of text, that will be further encrypt by AES and use as the payload in steganography. Based on A ...
1
vote
2answers
131 views

How would the use of an external lookup table affect file compression?

It occurred to me that, the way compression essentially works, is that you have a mapping of long patterns to short patterns, which you replace one way to compress and the other to decompress. My ...
1
vote
1answer
91 views

Was my Huffman coding solution wrong?

I finished my exam a moment ago and one of the question was to calculate Huffman coding for given probabilities: A: 0.15 B: 0.2 C: 0.55 D: 0.1 I encoded them as ...
0
votes
0answers
9 views

Quantile Summary Example

I am reading a note on quantile summary. I am not sure if I have already understood the definition of quantile summary. I am looking for concrete examples for the definition. Another question is ...
1
vote
1answer
47 views

Generate numeric or string ID for a sequence of elements

How to generate a numeric or string id(not very large text) for a sequence of elements where ordering doesn't matter. Example: [41,1001,32] should generate the ...
2
votes
1answer
37 views

Methods, Routines, or Algorithms To Optimize Selection of String Compression Methods

When encoding a a 2D Datamatrix barcode, I want the smallest output size. There are means to encode a compressed a string using some methods like C40. Reference: Here's a reference: https://en....
1
vote
3answers
108 views

Is there a method to compress all data without loss (lossless compression)?

I know that the answer is no but I'm not sure why. Here's where I started. We know that all data with length $n$ Bits and minimum $1$ Bit can be compressed, either lossless or lossy. But how do I ...
1
vote
1answer
72 views

Problem with determining the shape and direction of the Huffman Diagram

I have the phrase "abracadabra" and I want to encode it through the Huffman method. I first took the frequencies of each letters; $$a=5$$ $$b=3$$ $$c=1$$ $$d=2$$ $$r=2$$ But I'm not sure as to how the ...
0
votes
1answer
51 views

Intuitive way to understand “Run-Length Encoding”

Run-Length Encoding is the simple form of lossless data compression in which compression in which runs (execution) of data are stored as a single data value and count rather than as the original run (...
24
votes
11answers
9k views

Is von Neumann's randomness in sin quote no longer applicable?

Some chap said the following: Anyone who attempts to generate random numbers by deterministic means is, of course, living in a state of sin. That's always taken to mean that you can't generate ...
0
votes
0answers
70 views

Is it possible for a [futuristic] computer to contain the information of the whole universe?

(This is a question of information theory, data compression and entropy, so I believe it fits CS forum) Does the fact that the computer itself is a part of the universe make it logically impossible ...
2
votes
1answer
141 views

monotonically increasing codeword length in optimal (maybe Huffman) code for alphabet with monotonically decreasing frequencies

I'm working on exercise 16.3-5 of CLRS: Prove that if we order the characters in an alphabet so that their frequencies are monotonically decreasing, then there exists an optimal code whose codeword ...
1
vote
0answers
31 views

Using less Random Access Memory

Suppose you were to compress data before it was sent to Random Access Memory. Wouldn't you technically be using less R.A.M?
3
votes
2answers
306 views

Representation of used space and free space in hard drives

I've read from this How data is physically stored in hard drives, that the North/South orientation of the magnetic medium represents data as 0 or 1 physically in the hard drive. Data is stored in ...
1
vote
1answer
28 views

What is the Code2 and other concepts of variable encoding in Coding Redundancy?

Am learning the concept of Coding Redundancy in image compression and am finding it hard to understand the table on page 3 of this document. All other explanations seem to follow the same symbols and ...
3
votes
1answer
201 views

Is there a limit to data compression without mentioning Kolmogorov complexity?

I want to develop a previous answer to Is there a known maximum for how much a string of 0's and 1's can be compressed?. I've looked at the Hutter Prize and various compression benchmarks. The ...
-1
votes
1answer
168 views

Universal Lossless Compression? [closed]

It is not possible to losslessly compress all files of size $n$ using a single algorithm, as there are more files of size $n (2^n)$ than of size $p, p: p < n ( 2^n-1)$. Via the pigeon hole ...
1
vote
1answer
112 views

Practicality of compressing data with hashing algorithms

I want to compress the string 0cc175b9c0f1b6a831c399e269772661. I can do so by storing the string a, and, when decompressing, using a as input for the MD5 hash algorithm to get the original string. I ...
1
vote
0answers
94 views

Compression of gaussian variables

Say I have 2 Gaussian sources X and Y. They are generated with mutivariate gaussian distribution with ...
1
vote
0answers
79 views

Which algorithms provide high compression ratios for bit matrices?

I have an x*y bit matrix where the total number of bits fluctuates between ~1,000,000 and ~20,000,000 bits. The rows are much smaller than the columns. An example matrix might be of size 1,000,000 x ...
1
vote
1answer
110 views

How can I compress data that represents a number's change over time?

I have a value that increases by unknown increments at unknown times. Given a time, I need to check how much it has increased between that time and now. I could simply store every time/increase pair ...
6
votes
1answer
420 views

Optional prefix code for the naturals

The naturals $\mathbb{N}$ can be encoded with a binary unary code such as $$ \begin{align} 1&=0_b\\ 2&=10_b\\ 3&=110_b\\ &... \end{align} $$ The length this the ...
0
votes
0answers
61 views

[Choosing tunable parameter M in Golomb/Rice Encoding]

I am a Computer Science student and I study Data Compression now. I read many methods but Golomb-Rice Encoding was not clear for me. I understand the method how it works but in the algorithm there is ...
1
vote
1answer
47 views

How to predict the next image in a sequence, or predict the deblurring of an image?

I have 3 versions of an image at lower resolutions - 480p, 720p, and 1080p. Is it possible to use those 3 images to predict the next highest resolution image (the 4k image)? My first guess was that ...
0
votes
1answer
55 views

Can I say is lossy compression to discard data having a way to recover it?

I'm working on a compression algorithm for a specific kind of data. I have found a way to discard (important) parts of the data during compression as I have also found a way to recover the missing ...
1
vote
0answers
35 views

Compressing dataset by cartesian products cover

I have the following problem and I wonder if there exist a solution (or some algorithm to approximate it, even if it's far from optimal, as long as it is tractable) to it. Say I have a set $V\...
0
votes
0answers
415 views

How does youtube do video quality change/video compression?

After uploading a high definition video in youtube, youtube automatically makes a low definition(standard definition) version of the video. I would like to know what algorithm they use to reduce the ...