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Questions tagged [lossless-compression]

Lossless data compression is a class of data compression algorithms that allows the original data to be perfectly reconstructed from the compressed data.

Lossless data compression is used in many applications. For example, it is used in the ZIP file format and in the GNU tool gzip. It is also often used as a component within lossy data compression technologies (e.g. lossless mid/side joint stereo preprocessing by the LAME MP3 encoder and other lossy audio encoders).

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Prediciting time or compression ratio for lossless compress of a file?

How would one be able to predict execution time and/or resulting compression ratio when compressing a file using a certain lossless compression algorithm? I am especially more concerned with local compression, since if you know time and compression…
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How to compress objects into strings without losing too much information

Trying to figure out how to make a class that can create objects based on text files. If the interface Readable has the method String asString(), and the method Readable read(String s) in a class is to construct a Readable object based on the string…
MRoads
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Flip jpeg Image loss quality

I flip a image(12M), find the image size increase to 26M and the image format is changed to png. I save it to jpeg with the imageformat but the image size reduce to 2M. the code as following. public void Flip(Bitmap map) { …
conger
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Adding Smush.it to my image resizing script

Here's a PHP snippet from my class called 'Image'. Here is the full function inside my class protected function _output( $save_in = null, $quality, $filters = null ) { switch ($this->_mime_type) { case self::IMAGETYPE_JPEG : case…
NotAnotherCliche
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How can we read Lossless compressed JPEG images

I have some medical images and that was compressed as lossless images. These images can read only in matlab and accusoft Java API. How we can load these type of images in java? My current code is: Image img = null; ImageInputStream iis = new…
Lijo Joseph
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Compression of ODB files

I have a requirement to compress large ODB files which measure >1GB. I have used LZMA algorithm and could compress upto 22%. Is there a better way to compress these types of files with better compression ratio? The compression has to be loss-less.
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Windowing and lossless compression

I'm studying how FLAC works, although my question is valid for any lossless codec. I wonder how may a codec be lossless if the original signal is multiplied by a window which is not rectangular. I think this operation will modify the stream that we…
baister
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Compression Image

I am having SQL Server2005 Database where half of the data is Image which isin various formats. I want to convert all the image into jpeg2000 format and want to resize(reduce the size) the Images also. The front end application is made on VC++/MFC…
user215390
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Exploiting redundancy among JPG images

I wish to exploit redundancy among a set of similar colored JPG images. Set redundancy compression has been used successfully for similar 8-bit grayscale images. They basically find the MAX and MIN of a set of images and encode the original images…
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Compute the compression ratio for Huffman algorithm

I used this code HuffmanCodeto compress this…
lena
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pngData() file save is lossy or lossless

We are saving image as png file in swift as below pngData().write(fileURL,atomic) The file saved is lossy or lossless ? I checked for any tools online but did not find answers.
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Optimize images - Losslessly compress images in php

Images are stored in a different server than the one i use. Is there a way to losslessly compress them using php and after compression show the images to my site without having to download the images to my server and store them? I do not have any…
stefanosn
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ffmpeg png to png quality loss

I did a python script that managed to unshuffle a shuffled (png) image according to a specific pattern, that python script uses ffmpeg and does 12 encodes to unshuffling it (by cropping a specific part and pasting it over the existing picture). As…
kilo
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What is the difference between shannon fano and huffman algorithm?

It look likes almost similar to me except top down and Bottom-Up parsing . Can anyone explain ?
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mysql innodb multi-row database compression not supported?

MYSQL's InnoDb storage engine supports compression. However it seems to be only compressing each row separately... which ignores redundancy between rows... Can multi-row compression be enabled with mysql? My raw table size is 1.2 GB... however the…
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