图片轻量级压缩主要是通过imagemagick软件来实现，我们通过homebrew软件来安装
1. 安装homebrew
命令行输入：/usr/bin/ruby -e “$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)”
/usr/bin/ruby -e "$(curl -fsSL [https://raw.githubusercontent.com/Homebrew/install/master/install)](https://raw.githubusercontent.com/Homebrew/install/master/install))"
下载进度 ==> /usr/bin/sudo /bin/chmod g+rwx /Users/lixuewen/Library/Caches/Homebrew ==> /usr/bin/sudo /usr/sbin/chown lixuewen /Users/lixuewen/Library/Caches/Homebrew ==> Downloading and installing Homebrew... remote: Counting objects: 108116, done. remote: Compressing objects: 100% (17/17), done. remote: Total 108116 (delta 5), reused 14 (delta 5), pack-reused 108093 Receiving objects: 100% (108116/108116), 24.52 MiB | 34.00 KiB/s, done. Resolving deltas: 100% (79025/79025), done. From https://github.com/Homebrew/brew
如果提示出错了Error: /usr/local/Cellar is not writable. You should change the
ownership and permissions of /usr/local/Cellar back to your
user account:
输入下面的命令行 sudo chown -R $(whoami) /usr/local/Cellar
然后继续安装输入上面的安装指令
检测是否安装成功
brew
如果安装成功了，会返回如下命令
brew search [TEXT|/REGEX/]
brew info [FORMULA...]
brew install FORMULA...
brew update
brew upgrade [FORMULA...]
brew uninstall FORMULA...
brew list [FORMULA...]
Troubleshooting:
brew config
brew doctor
brew install --verbose --debug FORMULA
Contributing:
brew create [URL [--no-fetch]]
brew edit [FORMULA...]
Further help:
brew commands
brew help [COMMAND]
man brew
https://docs.brew.sh
2 安装安装x11，因为muntain lion已经删除了x11
https://www.xquartz.org
3 安装完xQuartz之后开始安装ghostscript，这个linux本来就安装了，但是mac没
brew install ghostscript
Updating Homebrew... ==> Installing dependencies for ghostscript: jpeg, libtiff, little-cms2 ==> Installing ghostscript dependency: jpeg ==> Downloading https://homebrew.bintray.com/bottles/jpeg-9c.high_sierra.bottle.tar.gz ######################################################################## 100.0% ==> Pouring jpeg--9c.high_sierra.bottle.tar.gz 🍺 /usr/local/Cellar/jpeg/9c: 21 files, 724.5KB ==> Installing ghostscript dependency: libtiff ==> Downloading https://homebrew.bintray.com/bottles/libtiff-4.0.9_4.high_sierra.bottle.tar ######################################################################## 100.0% ==> Pouring libtiff--4.0.9_4.high_sierra.bottle.tar.gz 🍺 /usr/local/Cellar/libtiff/4.0.9_4: 246 files, 3.5MB ==> Installing ghostscript dependency: little-cms2 ==> Downloading https://homebrew.bintray.com/bottles/little-cms2-2.9.high_sierra.bottle.1.t ######################################################################## 100.0% ==> Pouring little-cms2--2.9.high_sierra.bottle.1.tar.gz 🍺 /usr/local/Cellar/little-cms2/2.9: 18 files, 1MB ==> Installing ghostscript ==> Downloading https://homebrew.bintray.com/bottles/ghostscript-9.23.high_sierra.bottle.ta ######################################################################## 100.0% ==> Pouring ghostscript--9.23.high_sierra.bottle.tar.gz 🍺 /usr/local/Cellar/ghostscript/9.23: 679 files, 64.3MB
4.最后安装imagemagick
brew install imagemagick
输入命令进行压缩
$ cd /Users/lixuewen/Desktop/未命名文件夹\ 2
$ find . -iname "*.png" -exec echo {} \; -exec convert {} -quality 95 {} \;
一些其他用法
更改文件类型
$ convert input.jpg output.png
1）增加有色边
convert -bordercolor red -border 25x25 image.jpg image.gif
2）加亮或变暗图片边缘，以增强3D效果
convert -raise 25 image.jpg image.gif
3）在图片周围增加装饰性框架。
convert -mattecolor gray -frame 25x25 image.jpg image.gif
4）在图片边缘增加升、降斜角
convert -mattecolor gray -frame 25x25+0+25 image.jpg image.gif
convert -mattecolor gray -frame 25x25+25+0 image.jpg image.gif
5)将gif文件分析为一系列的单个图片
convert animation.gif frame%02d.gif
6)创建一张空白图片
convert -size 800x600 xc:"#ddddff" ltblue.ppm
convert -size 800x600 null:white white.ppm
convert in.png -threshold 100% black.ppm #<--与in.png同大小
Mac: 文件校验终端命令查看文件哈希值，md5
`MD5`
$ md5 文件路径
`SHA1`
$ shasum 文件路径
或者
$ openssl dgst -sha1 文件路径
`SHA256`
openssl dgst -sha256 文件路径
例：
bogon:未命名文件夹 2 lixuewen$ convert ert.jpg 111.png
bogon:未命名文件夹 2 lixuewen$ shasum /Users/lixuewen/Desktop/未命名文件夹\ 2/ert.jpg
`d0b0df3d1c1c72f7ea8f8512fb99e8aa7815fbc2` /Users/lixuewen/Desktop/未命名文件夹 2/ert.jpg
bogon:未命名文件夹 2 lixuewen$ shasum /Users/lixuewen/Desktop/未命名文件夹\ 2/111.png
`0a51d4c26c9102132038f54986ca2ff575b7e6ab` /Users/lixuewen/Desktop/未命名文件夹 2/111.png
bogon:未命名文件夹 2 lixuewen$ find . -iname "*.png" -exec echo {} \; -exec convert {} -quality 95 {} \;
./111.png
bogon:未命名文件夹 2 lixuewen$ shasum /Users/lixuewen/Desktop/未命名文件夹\ 2/111.png
`392477f3b6ecdb2baeee903117a22731d26a1dba` /Users/lixuewen/Desktop/未命名文件夹 2/111.png
bogon:未命名文件夹 2 lixuewen$
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