Warning: proc_open(): CreateProcess failed, error code - 267 in _imageapi_imagemagick_convert_exec() (regel 204 ...

When i try to enable the imagick toolkit I get several warnings:

* Notice: Undefined index: #post in imageapi_imagemagick_validate_path() (regel 86 van D:\Projecten\Drupal7\www\sites\all\modules\imageapi\imageapi_imagemagick.module).

This one is already reproted in #937314: Undefined index: #post in imageapi_imagemagick_validate_path()

* Warning: proc_open(): CreateProcess failed, error code - 267 in _imageapi_imagemagick_convert_exec() (regel 204 van D:\Projecten\Drupal7\www\sites\all\modules\imageapi\imageapi_imagemagick.module).

I had a look a the code:

function _imageapi_imagemagick_convert_exec($command_args, &$output, &$errors) {
  ...
  // Specify Drupal's root as the working a working directory so that relative
  // paths are interpreted correctly.
  $drupal_path = $_SERVER['DOCUMENT_ROOT'] . dirname($_SERVER['SCRIPT_NAME'] ? $_SERVER['SCRIPT_NAME'] : $_SERVER['SCRIPT_FILENAME']);
  ...
}

* aside: According to the PHP manual . has a higher precedence than ? leading to a very weird expression
* DOCUMENT_ROOT won't work when running an aliased website
* In my case (Zend Server CE on Apache2 on Windows Vista) this expression works fine: realpath(dirname($_SERVER['SCRIPT_FILENAME']));

But the DRUPAL_ROOT define is of course the way to go:

  $drupal_path = DRUPAL_ROOT;