There are a lot of answers out there, as the landscape for this program and PHP have changed over time.
I am so cutting edge as to be using PHP 7.1 at the moment. At first I was copying DLLs all over the place like all of the instructions have you do. Luckily, all that is necessary is the latest PECL package and the corresponding version of Imagick for your system, which was the tricky part. You can't used the latest Imagick (version 7 at the time of writing this) if you want to use the PHP extension, until the extension is upgraded. You have to install a version of Imagick on your system that matches the PHP extension version.
As others have instructed, download the latest PECL package for imagick for your PHP version. Since I'm using the thread-safe x64 version of PHP 7.1, I want the 3.4.3RC1 package, the only one with a DLL for my version of PHP at this time.
Of these files, I only need to copy over php_imagick.dll
. Next, head over to http://windows.php.net/downloads/pecl/deps/ and download the latest Imagick for your system which is probably going to be the VC14 one at this point, for which it seems just a matter of installing the corresponding C++ Redistributable package on your system for it to work. Simply unzip the files and add the bin to your path. Again, if you have a newer version of Imagick, you'll want to replace it with this one because this is the one that will work with the php extension.
At this point, you should be able to restart apache and confirm that the imagick extension is enabled in the phpinfo. It should show you the version of Imagick for the PHP extension. Again, if the Imagick on your system in your path is a version that matches what is shown for the PHP extension, then you should see the list of supported formats that it is getting from the DLLs from the version 6 Imagick on your system. You will not need to copy them to apache bin or anywhere else, nor make a MAGICK_HOME folder.