场景：

主要解决：ImageMagick number of supported formats:0 。PHP Startup: Unable to load dynamic library ‘imagick’。这两种问题。

重点是设置完windows系统环境变量后，要重启或注销系统后，php才能正常识别imagick扩展。经过测试，php7.3、7.4、8.0此方法均适用，8.1未测试。

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完整步骤

1.使用php -m 命令查看php扩展加载情况。下图是没有加载imagick扩展。

2.到PECL网站下载imagick的windows扩展包。

3.选择对应版本的PHP扩展，下载到本地。我用的是Nginx1.23，所以我下载nts版本。

4.将下载的压缩包解压到本地，可以是任意位置。以前教程都是解压到C盘，经过我测试其实哪个位置都行，主要是设置好环境变量。

5.设置好imagick的位置的环境变量。如下图，注意路径要正确。

6.设置好以后，到PHP根目录，修改php.ini配置文件，增加一行，保存。

7.将php_imagick-3.7.0-8.0-nts-vs16-x64文件夹中的dll扩展文件，复制到php的ext文件夹下。

8.重启或者注销系统一下。（重要步骤，如果不重启直接去试imagick扩展，会出现奇奇怪怪问题。其他教程没有提到。）

10.验证扩展是否安装成功。以下是使用php -m 命令、phpinfo()、new Imagick() 三种方法进行验证。

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环境说明

Windows 10 X64 LTSC
PHP:8.0.2
Nginx 1.23
imagick扩展:php_imagick-3.7.0-8.0-nts-vs16-x64

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PHP官网的安装说明（Apache例子）

If there is no “imagick” section or “supported format” is 0,
something went wrong.

I initially followed:
http://php .net/manual/en/imagick.installation.php
but after installation, PHPInfo under imagick shows
number of supported formats = 0

So I followed these steps, clobbered from various sources
to get it to work.

1. Open PHPInfo and check:
   Architecture = x86 or x64
   Thread Safety = yes or no

2. Download ImageMagick from:

   http://windows.php.net/downloads/pecl/deps/

   In my case I downloaded: ImageMagick-6.9.3-7-vc11-x86.zip
   because the Architecture under PHPInfo is x86
   as for vc11 or vc14
   search google for “visual c++ 11 runtime” or
   “visual c++ 14 runtime” and install it

3. Unzip and copy all dlls from the bin subfolder to the
   Apache bin directory. It’s a bunch of CORE_RL_.dll
   and IM_MOD_RL_.dll plus a few other dlls.

   In my case, I installed UwAmp in C:\UwAmp, so:
   (from zip) bin/*.dll --> C:\UwAmp\bin\apache\bin
   4. Goto:

   http://pecl.php.net/package/imagick

   as of today, latest is 3.4.1 so I went to:
   http://pecl.php.net/package/imagick/3.4.1/windows

   My PHP version is: 5.6.18, and Thread Safety is Yes from
   Step #1, so I downloaded:
   5.6 Thread Safe (TS) x86
   I got: php_imagick-3.4.1-5.6-ts-vc11-x86.zip

4. Unzip and copy “php_imagick.dll” to the php extension folder:

   In my case:
   php_imagick.dll --> C:\UwAmp\bin\php\php-5.6.18\ext

   Note: this ZIP also contains dlls which other guides says
   to extract to the extension folder of apache.
   NO NEED TO DO IT. Step #3 has taken care of it.

5. Edit “php.ini” and add at the very end (could be
   anywhere I suppose):

   [Imagick]
   extension=php_imagick.dll

   For super newbies: click the edit button in the UwAmp UI,
   “php_uwamp.ini” will open and edit it. It will be copied to
   the correct php.ini when UwAmp is restarted. I had
   trouble at first since there are several php*.ini scattered
   all over.

6. Restart Apache

7. Check PHPInfo
   scroll to section (or find): imagick
   number of supported formats: 234

Hope this helps.

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参考

在 Windows 10 64 位、PHP 7.4.6 中，报错：PHP Warning: PHP Startup: Unable to load dynamic library ‘imagick’

ImageMagick安装配置（PHP官网）