(PECL imagick 2.0.0)
Imagick::cropImage — Extracts a region of the image
$width
   , int $height
   , int $x
   , int $y
   )Extracts a region of the image.
width
     The width of the crop
height
     The height of the crop
x
     The X coordinate of the cropped region's top left corner
y
     The Y coordinate of the cropped region's top left corner
   成功时返回 TRUE .
  
错误时抛出 ImagickException .