Questions tagged [compression]

The name given to the process of encoding data such that it uses lesser number of bits as compared to the original representation.

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Looking for help simplifying a general purpose compression function

The following is a general purpose file compression function with the following features: It can take either a single file or directory as the source input It defaults to the source directory when to ...
Christian Fitzner's user avatar
0 votes
1 answer
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Comparing video recording algorithms in Java: no-compression vs. naive diff compressor

Usage of the program is in Facebook. Intro In this JavaFX program, a user is presented with a white canvas with a black circle at the center of the canvas. Then, the user has 10 seconds to record a ...
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Most compact data format for a shopping cart

I'm trying to build a format that can represent the user's cart on my website in the most compact way. The website is related to computer parts and there are 23 product categories. Each product has an ...
Raees Iqbal's user avatar
3 votes
2 answers
1k views

Huffman Coding implementation in C++

Here is an implementation of compression with Huffman coding. It works well by my testing. It compresses a 1 GB string in about 30 seconds, and decompresses in about 15 seconds with VisualStudio 2022 &...
Aykhan Hagverdili's user avatar
1 vote
1 answer
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Optimal Jelly string compressor in Rust

I'm writing some small programs to practice Rust, and this one's a string compressor for the golfing language Jelly (unofficial spec). It involves some non-ASCII stuff and bigints (from the ...
Radvylf Programs's user avatar
4 votes
1 answer
283 views

Python script for zlib decompression

I'm looking for feedback/improvement on code that I wrote. It's a function that scans a file for zlib headers and returns the header, offset, and decompressed data. In main, below the function, I use ...
792f8NFF's user avatar
6 votes
2 answers
994 views

Huffman coding, using vector<bool>

This is my draft implementation of Huffman encoding & decoding. I'd appreciate any feedback, but have a couple specific questions: I wrote the code assuming vector represents each bool with a ...
Uri Raz's user avatar
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Huffman coding implementation in java

I wrote a simple huffman coding algorithm for learning and practice. I just used the technique given on the wikipedia page. Could you tell me my missing points and mistakes? Node.java ...
gedofgont's user avatar
7 votes
1 answer
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Decompress tar.gz file in Go

I want to extract tar.gz file and store the contents in the same directory. I got below method which does the job but I wanted to see if there is any way to improve ...
AndyP's user avatar
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Generic Huffman Encoding

For my first Rust exercise I decided to re-implement a project I wrote in C++ for my data structures class a few years ago, plus make it generic. I am looking for all suggestions, but I am primarily ...
zmjackson's user avatar
1 vote
3 answers
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Run-length coder

I have this code, which counts only adjacent letters in a string and returns the count of each letter. ...
uday8486's user avatar
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Linux backup script written in bash for tar

This is my first attempt at scripting with bash. I am running Ubuntu server, so I don't get to use all the gui back ups out there. Besides, tar works fine for personal use. Please let me know of any ...
Riv's user avatar
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Huffman compressor in plain C

I recently picked up C, because I am getting tired of the hell that is Java Enterprise development. I decided that writing a Huffman compressor will be a great little exercise, and I have always ...
Teodor Dyakov's user avatar
2 votes
2 answers
425 views

Numeronym generation

Problem statement I need to generate numeronyms from a string, let's say qwerty as follows: qwerty q1erty q2rty q3ty q4y Code ...
Vinay Sharma's user avatar
8 votes
2 answers
385 views

Huffman encoding bitcodes display

So, the concept of the code is simple. Take any file, read the binary character counts and construct a Huffman tree, and then output the bit code of each character (displayed as its 8-bit value). This ...
Jack Avante's user avatar
2 votes
2 answers
507 views

Priority queue implementation on C. (For Huffman Coding)

I trying to implement Huffman Codes on C. And, since my previous attempt failed, I decided to approach the issue more responsibly. So I'm asking for feedback on my implementation of the priority queue ...
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SevenZipCompressor Utility class that uses Commons-Compress to compress and uncompress 7zip archives

I wrote a Compressor utility class to generate 7zip files containing everything in a specific directory. The problem is that it's an order of magnitude slower than both archiving the directory using ...
Nzall's user avatar
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3 votes
2 answers
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Slow Huffman Code in pure Python

I was working on writing a fast implementation of a simple Huffman code compression of text. The idea was to write it using only the standard library, but I can't seem to find a way to make it faster. ...
Albert Alonso's user avatar
6 votes
1 answer
1k views

LZ77 compressor and decompressor in C++

I've written working LZ77 algorithm implementation which uses linked lists (they help to look for matching substrings faster). I'd like to get some feedback on my code's quality and also information ...
Maxim Voloshin's user avatar
4 votes
1 answer
570 views

LZW Compression Library

I wrote a library that implements LZW compression and decompression. A goal of this project was to help me acquaint myself with modern C++ development practices (I primarily come from a Java ...
user129137's user avatar
11 votes
2 answers
2k views

Huffman encoding

The Huffman-Algorithm The Huffman-Algorithm, named after David A. Huffman who first published this algorithm in 1952, is a algorithm for lossless data compression. As most encoding-methods, the words ...
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4 votes
1 answer
341 views

Huffman encoding as Unix style command line utility

After watching Tom Scott explain Huffman coding in this YouTube video, I wanted to implement it myself. I want to use this project to further my understanding of Python. Additionally this tool should ...
endofline's user avatar
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Fast compression using a thread pool

This is my latest effort on RFC 1951 compression ( the widely-supported compression standard ) in Rust. It uses 2 extra threads to compute the LZ77 matches and the checksum in parallel with the ...
George Barwood's user avatar
1 vote
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RFC 1951 "Inflate" (de-compression)

My exploration of Rust continues. I'm quite pleased with the 2-step table lookup for decoding variable bit-length codes here, for some reason I found this tricky to work out, but now it's done I like ...
George Barwood's user avatar
10 votes
3 answers
2k views

Compression Library for C using Huffman Coding

This is an update to a question I posed nearly two years ago about my implementation of Huffman Coding which I had written in C. Since then I have had time to grow as a programmer and have managed to ...
jess's user avatar
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2 votes
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LZ77 Encoding and Decoding in Haskell

I am trying to learn Haskell and figured I would kill two birds with one stone and also learn about data compression. My ultimate goal is to implement the DEFLATE compression algorithm in Haskell. To ...
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7 votes
0 answers
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Feedback on LZSS implementation

Recently, I've been trying to get back into Haskell, so I tried coding up a LZSS implementation. I realize this is much more easily implemented imperatively, but I wanted to challenge myself. The last ...
greenjaed's user avatar
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2 answers
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Huffman Encoding in Javascript

So, I've implemented Huffman Encoding in JavaScript, you can see it live here. Here is the code: ...
FlatAssembler's user avatar
2 votes
0 answers
266 views

How can I make my LZ77 algorithm to compress faster or to compress more?

So, I am trying to create a PNG compression library, and to do that I need to use the DEFLATE algorithm; DEFLATE consists of two parts, the LZ77 compression, and the Huffman Compression. Currently, my ...
polmonroig's user avatar
1 vote
0 answers
14 views

Compressing and encrypting file systems for backups

I am currently backing up remote OS' while preserving the permissions using rsync: rsync -aAX --numeric-ids --delete ... [email protected]:/ /backup/server/ Now I ...
maxisme's user avatar
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3 votes
0 answers
190 views

Doing image compression with Neural Network AutoEncoders

I wanted to create an image compressor using Machine Learning and started work on an "AutoEncoder". This is a type of Neural Network which takes in the image and creates a compressed vector form. It ...
neel g's user avatar
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4 votes
1 answer
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Minimalist context compressor

I am working on an implementation of the minimalist compression method. The method is based on context modeling, followed by a simple entropy coder (Golomb-Rice coder). The context model uses a single ...
DaBler's user avatar
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1 answer
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Minimalist Golomb-Rice coder

I have implemented a very simple but robust implementation of the Golomb-Rice coding. To understand my motivation, see the minimalist data compressor that is based on this. At the moment, the ...
DaBler's user avatar
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6 votes
2 answers
272 views

Compressing large jpeg images

I'm working with thousands of large image files in a regularly updated library. The following script does the job (on average reduces my file size ~95%) but costs me around 25 seconds to compress one ...
cburchie's user avatar
4 votes
0 answers
83 views

Powershell optimization (scripts to run simultaneously)

I need some help here, I posted on stackoverflow and was directed here, just to put things in context, I am new to PowerShell, I have a task, that in simple terms, would take a csv with more than ...
Roi Samagoue's user avatar
7 votes
1 answer
2k views

LZ77 compression algorithm (general code efficiency)

I'm implementing LZ77 compression algorithm. To compress any file type, I use its binary representation and then read it as chars (because 1 ...
asymmetriq's user avatar
8 votes
1 answer
471 views

Brainfuck compressor in Python

Just for fun, I created a script called TinyBF which can compress Brainfuck programs into a format half their size. For example, take a famous hello world program clocking in at 78 bytes: ...
moltarze's user avatar
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8 votes
1 answer
1k views

LZ77 compression (also longest string match)

So, I'm implementing LZ77 compression algorithm. To compress any file type, I use its binary representation and then read it as chars (because 1 ...
asymmetriq's user avatar
7 votes
1 answer
344 views

Loading BitmapImages out of a Zip file

I'm working on a personal project to get better with C#, and as part of that I have a zip file with 20 or so images saved inside. I want to load those images out of the zip file and display them in my ...
Lightning759's user avatar
5 votes
3 answers
162 views

File compression project

I wrote a general purpose file compression program out of curiosity, but I am concerned about readability. I don't know if the variable names are useful, and whether most of the comments are unneeded ...
Hashew's user avatar
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3 votes
1 answer
81 views

File compressor

I have written a file compressor in python. The program generates a file filled with sequences of the same character with a random length, and compresses that file. I would like feedback on code ...
Linny's user avatar
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2 votes
2 answers
3k views

Run length encoding in C#

This is the original question: https://www.geeksforgeeks.org/run-length-encoding/ Given an input string, write a function that returns the Run Length Encoded string for the input string. For ...
Gilad's user avatar
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2 votes
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Google drive backup robot

I have a lot of files. I care about those files. I also care about good programming practices and learning proper python. Given the described context, it seemed appropriate to implement my own ...
sage's user avatar
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0 votes
1 answer
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Uncompressing a list with some run-length-encoded elements

Regarding the following code ...
mwal's user avatar
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3 votes
1 answer
103 views

Print a string of characters with their occurrences

I have worked out a solution for this problem, however I am trying to reach an O(1) solution without the use of two for loops. The output should read as a3b2c4d1 ...
Jeff Voss's user avatar
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4 votes
1 answer
294 views

First Huffman Compression Algorithm in C++

I decided to take up learning c++ recently, so I coded a Huffman compression algorithm. I'm particularly interested in critique of my c++ techniques (pointers, references, best practices, etc), but I ...
James Delaney's user avatar
6 votes
3 answers
6k views

Huffman Code in C++

This is my version of the Huffman Codes. ...
Stevan Milic's user avatar
4 votes
2 answers
882 views

WPF Bitmap / BitmapFrame to multi-page / multi-frame TIFF with JPEG encoding

I was searching for a long time how to write multi-page TIFFs with the JPEG encoding. TIFFs support JPEG encoded frames but the built-in encoder in .NET Framework does not have JPEG as a compression ...
geometrikal's user avatar
5 votes
2 answers
154 views

Using two threads to increase RFC1951 Deflate compression performance

I have modified my implementation of RFC 1951 "Deflate" compression to use two threads. One thread performs the LZ77 matching, looking for sequences of at least three bytes that occur earlier in the ...
George Barwood's user avatar
1 vote
2 answers
129 views

Optimised code to compute Huffman codes when implementing RFC 1951

I found a trick to significantly reduce the time needed to compute Huffman codes in my implementation of RFC1951. I was slightly surprised to find it slightly improves compression as well, something ...
George Barwood's user avatar