各种压缩软件的对比情况：

http://jamiemason.github.io/ImageOptim-CLI/comparison/png/photoshop/desc/

压缩率较高的为 ImageAlpha的有损压缩 加上 ImageOptim的无损压缩，二者要要先后顺序，

嫌麻烦的话，少量图片也可以使用在线工具：TinyPNG

此工具有api，但是有限制，每个key每月300次，再多就要收费

ImageOptim

进入官网

无损压缩,GUI + Command Line(有GUI软件，也有命令行)

使用此工具，需要关闭Xcode自带的图片压缩功能，否则Xcode压缩图片后反而会增加

Xcode设置见教程

Command Line :https://imageoptim.com/command-line.html

include：

• PNGOUT
• Zopfli,
• Pngcrush,
• AdvPNG,
• OptiPNG,
• JpegOptim,
• jpegrescan,
• jpegtran,
• Gifsicle.

ImageAlpha

进入官网

有损压缩，完成后，接着使用上面的ImageOptim来再次压缩效果更好

GUI + Command Line

include:

• pngquant,见下面
• pngnq-s9

pngquant

进入官网

Command Line ,被很多软件集成，较为底层。

http://pngquant.org/

集成该命令的软件，include:

GUI

• ImageAlpha, 如上 — Mac OS X GUI for pngquant and other tools
• SuperPNG Photoshop plug-in — Mac and Windows. Comparison with “Save for Web”
• PNGoo — Windows GUI for batch conversion
• Pngyu — Mac OS X and Windows GUI with batch processing option
• TinyPNG and Kraken.io — on-line interfaces for pngquant

Command-line 下载链接

• Binary for Mac OS X (v2.3.3)
• Binary for Windows (v2.3.1)
• Package for Debian testing Important: don‘t use version 1.0-4.1 from Debian stable! Only install 2.0+ from “jessie”.
• Various Linux packages, RPM spec
• Latest source code as tarball (to build on other platforms)

Trimage

进入官网

跨平台，GUI + Command Line

Trimage is a cross-platform GUI and command-line interface to optimize image files for websites, using optipng, pngcrush, advpng and jpegoptim, depending on the filetype (currently, PNG and JPG files are supported). It was inspired by imageoptim. All image files are losslessy compressed on the highest available compression levels, and EXIF and other metadata is removed. Trimage gives you various input functions to fit your own workflow: A regular file dialog, dragging and dropping and various command line options.

include:

• optipng,
• Pngcrush,
• AdvPNG,
• JpegOptim,

kraken

https://kraken.io/

在线压缩，收费，支持试用

tinypng

https://tinypng.com/

在线压缩，收费，支持试用

iOS开发中，PNG图片的各种压缩软件，以及压缩率对比