LZW-Compress | LZW压缩算法的完整实现

by FinalTheory C++ Version: Current License: No License

X-Ray Key Features Code Snippets Community Discussions(3)Vulnerabilities Install Support

kandi X-RAY | LZW-Compress Summary

LZW-Compress is a C++ library. LZW-Compress has no bugs, it has no vulnerabilities and it has low support. You can download it from GitHub.

LZW压缩算法的完整实现

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Quality

Security

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Support

LZW-Compress has a low active ecosystem.

It has 8 star(s) with 1 fork(s). There are 1 watchers for this library.

It had no major release in the last 6 months.

There are 1 open issues and 0 have been closed. There are no pull requests.

It has a neutral sentiment in the developer community.

The latest version of LZW-Compress is current.

Quality

LZW-Compress has no bugs reported.

Security

LZW-Compress has no vulnerabilities reported, and its dependent libraries have no vulnerabilities reported.

License

LZW-Compress does not have a standard license declared.

Check the repository for any license declaration and review the terms closely.

Without a license, all rights are reserved, and you cannot use the library in your applications.

Reuse

LZW-Compress releases are not available. You will need to build from source code and install.

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LZW-Compress Key Features

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LZW-Compress Examples and Code Snippets

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Community Discussions

Trending Discussions on LZW-Compress

Why using unix-compress and go compress/lzw produce different files, not readable by the other decoder?

Decompress TIFF-File

Decoding TIFF LZW codes not yet in the dictionary

QUESTION

Why using unix-compress and go compress/lzw produce different files, not readable by the other decoder?

Asked 2020-Apr-17 at 16:06

I compressed a file in a terminal with compress file.txt and got (as expected) file.txt.Z

When I pass that file to ioutil.ReadFile in Go,

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ANSWER

Answered 2017-Mar-19 at 17:41

A .Z file does not only contain LZW compressed data, there is also a 3-bytes header that the Go LZW code does not generate because it is meant to compress data, not generate a Z file.

Source https://stackoverflow.com/questions/42889664

QUESTION

Decompress TIFF-File

Asked 2019-Aug-10 at 20:45

I have a Tiff-File (BigTiff, because it is ~8GB). Now I want to scale it down (4K Resolution) and I am struggling to find the correct software. When I find a software or lib which can handle Tiff-Files they have Problems with BigTiff, Dimesion (My file has a dimension > 65500 Pixels) or the LZW-Compression.

Can somebody give me a hint for a good software or lib which scales down the Tiff-File or can convert it to a other File-Format? (Linux/Mac preferred)

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ANSWER

Answered 2019-Aug-07 at 11:38

One of the software I use is "convert" from ImageMagick. It is standard software in Ubuntu and it's completely command line.

To use it:

Source https://stackoverflow.com/questions/57393381

QUESTION

Decoding TIFF LZW codes not yet in the dictionary

Asked 2019-Apr-16 at 20:37

I made a decoder of LZW-compressed TIFF images, and all the parts work, it can decode large images at various bit depths with or without horizontal prediction, except in one case. While it decodes files written by most programs (like Photoshop and Krita with various encoding options) fine, there's something very strange about the files created by ImageMagick's convert, it produces LZW codes that aren't yet in the dictionary, and I don't know how to handle it.

Most of the time the 9 to 12-bit code in the LZW stream that isn't yet in the dictionary is the next one that my decoding algorithm will try to put in the dictionary (which I'm not sure should be a problem although my algorithm fails on an image that contains such cases), but at times it can even be hundreds of codes into the future. In one case the first code after the clear code (256) is 364, which seems quite impossible given that the clear code clears my dictionary of all codes 258 and above, in another case the code is 501 when my dictionary only goes up to 317!

I have no idea how to deal with it, but it seems that I'm the only one with this problem, the decoders in other programs load such images fine. So how do they do it?

Here's the core of my decoding algorithm, obviously due to how much code is involved I can't provide complete compilable code in a compact manner, but since this is a matter of algorithmic logic this should be enough. It follows closely the algorithm described in the official TIFF specification (page 61), in fact most of the spec's pseudo code is in the comments.

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ANSWER

Answered 2019-Apr-16 at 20:37

The bogus codes come from trying to decode more than we're supposed to. The problem is that a LZW strip may sometimes not end with an End-of-Information 257 code, so the decoding loop has to stop when a certain number of decoded bytes have been output. That number of bytes per strip is determined by the TIFF tags ROWSPERSTRIP * IMAGEWIDTH * BITSPERSAMPLE / 8, and if PLANARCONFIG is 1 (which means interleaved channels as opposed to planar), by multiplying it all by SAMPLESPERPIXEL. So on top of stopping the decoding loop when a code 257 is encountered the loop must also be stopped after that count of decoded bytes has been reached.

Source https://stackoverflow.com/questions/55674925

Community Discussions, Code Snippets contain sources that include Stack Exchange Network

Vulnerabilities

No vulnerabilities reported

Install LZW-Compress

You can download it from GitHub.

Support

For any new features, suggestions and bugs create an issue on GitHub. If you have any questions check and ask questions on community page Stack Overflow .

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