First install ImageMagick-6.7.7-5-Q16-windows-dll that can be find here: http://ftp.sunet.se/pub/multimedia/graphics/ImageMagick/binaries/
For a safety chose install path that doesn't contain spaces.
Next download and unzip php_imagick.dll from http://www.peewit.fr/imagick/ it must be version for PHP 5.5 and TS(Thread Safe).
Move php_imagick.dll to xampp/php/ext
Add to php.ini line:
extension=php_imagick.dll
And optionally (I think it's optional but it can be required ;p) to httpd.conf (apache folder)
SetEnv MAGICK_HOME "C:\Your\Path\To\ImageMagick"
Next copy modules files from ImageMagick\modules\coders to .magick in your user folder
example path: C:\Users\userName\.magick
(to create .magick folder open C:\Users\yourProfileName in CMD and type: mkdir .magick)
Now run XAMPP, if it gives error try logout and login, and Imagick should work.
For test you can use one of examples listed here: http://php.net/manual/en/imagick.examples-1.php