(PECL imagick 2.0.0)
Imagick::resampleImage — Resample image to desired resolution
$x_resolution
   , float $y_resolution
   , int $filter
   , float $blur
   )Resample image to desired resolution.
x_resolution
y_resolution
filter
blur
   Returns TRUE on success.
  
Example #1 Imagick::resampleImage()
<?php
function resampleImage($imagePath) {
    $imagick = new \Imagick(realpath($imagePath));
    $imagick->resampleImage(200, 200, \Imagick::FILTER_LANCZOS, 1);
    header("Content-Type: image/jpg");
    echo $imagick->getImageBlob();
}
?>