php_imagemagick_image_crop.php

<?php
$crop = '';
if ($image_width / $image_height > $width / $height) {
        $crop .= ' -resize "x'.$height.'"';
        $resized_w = ($height / $image_height) * $image_width;
        $crop .= ' -crop "'.$width.'x'.$height.'+'.round(($resized_w - $width) / 2).'+0" +repage';
} else {
        $crop .= ' -resize "' . $width . 'x"'; 
        $resized_h = ($width / $image_width) * $image_height;
        $crop .= ' -crop "'.$width.'x'.$height.'+0+'.round(($resized_h - $height) / 2).'" +repage';
}       
?>