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{{NoteTA|G1=IT}}
{{校对翻译}}
{{Infobox software
| name = Zopfli Archive
| released = {{Start date|2013|02|df=yes}}
| latest release version = 1.0.1
| programming language = [[C (编程语言)|C]]
| operating system = [[跨平台]]
| license = [[Apache License]] 2.0
| genre = [[数据压缩]]
}}
'''Zopfli'''是一个[[数据压缩]]算法，可以将数据压缩为[[DEFLATE]]、[[gzip]]或[[zlib]]格式。<ref name="zopfli-home" />Zopfli被认为是目前压缩率最高的DEFLATE压缩算法。<ref name="Debian" />2013年2月，[[Google]]将Zopfli算法的一个参考实现以[[Apache许可证]]2.0发布为[[自由软件]][[函式庫|程序库]]。<ref name="GoogleDevBlog" />名称Zöpfli是[[瑞士德语]]“[[辫子面包|Zopf]]”（一种不加糖的花环面包）的[[指小]]形式。<ref name="name" />

== 属性和使用案例 ==
Zopfli可以输出DEFLATE原始数据流，也可以将DEFLATE数据封装为gzip或zlib格式。默认配置的15次迭代可被增加或减少，以平衡压缩耗时与效果。

在默认设置下，Zopfli的输出一般比zlib的最大压缩小3%至8%，但消耗约80倍时间。<ref name="GoogleDevBlog" /><ref name="lifehacker" />Zopfli的解压速度与zlib的解压速度不相上下。<ref name="zopfli-paper" />

由于其压缩速度显著较慢，zopfli不太适合实时压缩，一般用于静态内容的一次性压缩。<ref name="deanhume" /><ref name="theregister" />典型用途是提供[[Web]]内容，包括基于DEFLATE的[[HTTP压缩]]，或者使用在基于DEFLATE的文件格式，例如PNG和[[Web開放字型格式|WOFF]]字体文件。<ref name="IlyaGrigorik" />另一个用途是基于[[ZIP格式|ZIP]]的软件包文件下载和更新，例如[[APK|Android应用程序包]]（APK）和[[JAR (文件格式)|Java存档文件]]（JAR），尤其是用在移动网络。

== 技术 ==
使用高消耗的压缩技术可取得更高数据密度。该方法基于迭代[[熵 (信息论)|熵]]建模，以及一个[[最短路问题|最短路径]]搜索算法，凭借所有未压缩数据可能的DEFLATE表示法得到的[[图 (数学)|图]]，找到最低的位消耗路径。<ref name="thinkdigit" />

== 实现 ==
Google发布了一个用[[C语言|C]]语言编写的程序库参考实现。它可以按[[Apache许可证]]2.0的条款作为自由软件使用。<ref name="zopfli-home" />

为[[PHP]]创建的{{tsl|en|Wrapper_library|包装器}}：php_zopfli。<ref>{{Cite web|url=https://github.com/clickalicious/php_zopfli|title=clickalicious/php_zopfli · GitHub|accessdate=2015-09-29|author=|date=2015-03-03|publisher=Github.com|archive-date=2013-04-11|archive-url=https://archive.today/20130411005435/https://github.com/clickalicious/php_zopfli|dead-url=yes}}</ref>

一个用[[C♯|C#]]实现的Zopfli位于CompressSharper程序库的ZopfliDeflater.cs。<ref>{{Cite web|url=https://compresssharper.codeplex.com/SourceControl/latest#CompressSharper/CompressSharper/ZopfliDeflater.cs|title=CompressSharper - Source Code|accessdate=2015-09-29|date=2015-08-21|publisher=Compresssharper.codeplex.com|archive-date=2017-12-25|archive-url=https://web.archive.org/web/20171225193453/http://compresssharper.codeplex.com/SourceControl/latest#CompressSharper/CompressSharper/ZopfliDeflater.cs|dead-url=no}}</ref>

== 历史 ==
Zopfli基于Jyrki Alakuijala的一个算法。Google员工Jyrki Alakuijala和Lode Vandevenne撰写了一个zopfli的参考实现，2013年2月首次向公众发布。版本1.0.0发布于2013年4月25日。<ref name="release-1.0.0" />之后几个为PNG压缩的适配出现在[[GitHub]]，''ZopfliPNG''在2013年5月被提交到Google的zopfli参考实现。<ref name="ZopfliPNG" />

Zopfli的出现显示，Ken Silverman的KZIP是压缩率最有效的DEFLATE实现，以及[[7-Zip]]的deflater是压缩率最有效的自由许可之一。

== PNG优化 ==
因为PNG使用DEFLATE压缩层，Zopfli算法可用于压缩[[PNG]]文件。Zopfli的作者创建了一个名为ZopfliPNG的PNG优化工具。Zopfli算法也已被集成到其他PNG压缩优化工具，例如{{tsl|en|AdvanceCOMP|AdvanceCOMP}}工具套件中的advpng。<ref name="advpng" />

ZopfliPNG是目前缩减PNG大小最有效的优化器。

== 参见 ==
* [[Brotli]]

== 参考资料 ==
{{Reflist|30em|refs=<ref name="GoogleDevBlog">{{cite web |url=http://googledevelopers.blogspot.com/2013/02/compress-data-more-densely-with-zopfli.html |title=Compress data more densely with Zopfli - Google Developers Blog |publisher=Googledevelopers.blogspot.com |date=2013-02-28 |accessdate=2013-05-01 |archive-date=2016-03-08 |archive-url=https://web.archive.org/web/20160308094257/http://googledevelopers.blogspot.com/2013/02/compress-data-more-densely-with-zopfli.html |dead-url=no }}</ref> <ref name="zopfli-home">{{cite web |author= |url=https://github.com/google/zopfli |title=google/zopfli · GitHub |publisher=Github.com |date= |accessdate=2015-09-29 |archive-date=2022-03-18 |archive-url=https://web.archive.org/web/20220318184407/https://github.com/google/zopfli |dead-url=no }}</ref> <ref name="Debian">{{cite web |author= |url=https://packages.debian.org/jessie/zopfli |title=Debian - Details of package zopfli in jessie |publisher=Packages.debian.org |date= |accessdate=2015-09-29 |archive-date=2016-03-04 |archive-url=https://web.archive.org/web/20160304000209/https://packages.debian.org/jessie/zopfli |dead-url=no }}</ref> <ref name="name">{{cite web |author=Alexander Neumann |url=http://www.heise.de/-1814414.html |title=Zopfli: Neue Kompressionsbibliothek von Google | heise Developer |publisher=[[Heinz Heise|Heise.de]] |date= |language=de |accessdate=2015-09-29 }}{{dead link|date=2018年2月 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> <ref name="lifehacker">{{cite web |url=http://www.lifehacker.com.au/2013/03/a-look-at-zopfli-googles-open-source-compression-algorithm/ |title=A Look At Zopfli, Google's Open Source Compression Algorithm | Lifehacker Australia |publisher=Lifehacker.com.au |date=2013-03-03 |accessdate=2015-09-29 |archive-date=2020-10-24 |archive-url=https://web.archive.org/web/20201024034956/https://www.lifehacker.com.au/2013/03/a-look-at-zopfli-googles-open-source-compression-algorithm/ |dead-url=no }}</ref> <ref name="zopfli-paper">{{cite article |title=Data compression using Zopfli |last=Alakuijala |first=Jyrki |last2=Vandevenne |first2=Lode |url=http://aq.hao124.eu.org/files/d7471e59937ee9ac-u-AHR0cHM6Ly96b3BmbGkUZ29vZ2xlY29kZs5jb20vZmlSZXMvRGf0YV9jb21wcmVzc2lvbl91c2lUZ19Ab3BmbGkUcGRm.pdf |accessdate=2015-09-06 |archive-date=2016-03-05 |archive-url=https://web.archive.org/web/20160305074743/http://aq.hao124.eu.org/files/d7471e59937ee9ac-u-AHR0cHM6Ly96b3BmbGkUZ29vZ2xlY29kZs5jb20vZmlSZXMvRGf0YV9jb21wcmVzc2lvbl91c2lUZ19Ab3BmbGkUcGRm.pdf |dead-url=yes }}</ref> <ref name="deanhume">{{cite web |url=http://deanhume.com/home/blogpost/improved-compression-ratios-using-zopfli/9125 |title=Improved Compression Ratios Using Zopfli |author=Dean Hume |date=2015-06-01 |accessdate=2015-09-06 |archive-date=2017-09-29 |archive-url=https://web.archive.org/web/20170929170425/http://deanhume.com/Home/BlogPost/improved-compression-ratios-using-zopfli/9125 |dead-url=no }}</ref> <ref name="theregister">{{cite web|url=http://www.theregister.co.uk/2013/03/01/zopfli_compression/|title=Google open sources very slow compression algorithm|work=The Register|first=Simon|last=Sharwood|year=2013|access-date=2016-07-03|archive-date=2019-02-20|archive-url=https://web.archive.org/web/20190220181421/https://www.theregister.co.uk/2013/03/01/zopfli_compression/|dead-url=no}}</ref> <ref name="IlyaGrigorik">{{cite web |url=https://plus.google.com/+IlyaGrigorik/posts/1sxencNkbNS |author=Ilya Grigorik |title=Google Fonts recently switched to using new Zopfli compression algorithm |publisher=Google+ |date=2014-01-09 |accessdate=2015-06-06 |archive-date=2019-01-09 |archive-url=https://web.archive.org/web/20190109002808/https://plus.google.com/+IlyaGrigorik/posts/1sxencNkbNS |dead-url=no }}</ref> <ref name="thinkdigit">{{cite web |author= |url=http://www.thinkdigit.com/Internet/Zopfli-Googles-new-data-compression-algorithm_13707.html |title=Zopfli: Google's new data compression algorithm | Digit.in |publisher=Thinkdigit.com |date=2013-03-01 |accessdate=2015-09-29 |archive-date=2013-07-08 |archive-url=https://web.archive.org/web/20130708033145/http://www.thinkdigit.com/Internet/Zopfli-Googles-new-data-compression-algorithm_13707.html |dead-url=no }}</ref> <ref name="release-1.0.0">{{cite web |url=https://github.com/google/zopfli/releases/tag/zopfli-1.0.0 |title=Release Zopfli-1.0.0 |date=2013-04-25 |publisher=Github.com |accessdate=2015-09-06 |archive-date=2020-10-23 |archive-url=https://web.archive.org/web/20201023114634/https://github.com/google/zopfli/releases/tag/zopfli-1.0.0 |dead-url=no }}</ref> <ref name="ZopfliPNG">{{cite web |author= |url=https://github.com/google/zopfli/commit/337d27f25ef15a6cf34fef2acd0613fddc411cb1 |title=ZopfliPNG : Google/zopfli@337d27f |publisher=Github.com |date= |accessdate=2015-09-29 |archive-date=2019-02-18 |archive-url=https://web.archive.org/web/20190218131333/https://github.com/google/zopfli/commit/337d27f25ef15a6cf34fef2acd0613fddc411cb1 |dead-url=no }}</ref> <ref name="advpng">{{cite web |author=Andrea Mazzoleni |url=http://advancemame.sourceforge.net/doc-advpng.html#3 |title=Advance Projects |publisher=Advancemame.sourceforge.net |date= |accessdate=2015-09-29 |archive-date=2015-06-28 |archive-url=https://web.archive.org/web/20150628183641/http://advancemame.sourceforge.net/doc-advpng.html#3 |dead-url=no }}</ref>}}

== 外部链接 ==
* [https://github.com/google/zopfli Project page] {{Wayback|url=https://github.com/google/zopfli |date=20220318184407 }} on GitHub, [http://zopfli.t0r.org online implementation] {{Wayback|url=http://zopfli.t0r.org/ |date=20191201051346 }}
* [http://www.techrepublic.com/blog/the-enterprise-cloud/googles-zopfli-compression-algorithm-extract-higher-performance-from-your-compressed-files/ Google's Zopfli Compression Algorithm: Extract higher performance from your compressed files] {{Wayback|url=http://www.techrepublic.com/blog/the-enterprise-cloud/googles-zopfli-compression-algorithm-extract-higher-performance-from-your-compressed-files/ |date=20211023113015 }} – TechRepublic.com

{{压缩方法}}
[[Category:自由發展元件與函式庫]]
[[Category:无损压缩算法]]

Zopfli - 版本历史

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