Call to undefined method yii\imagine\Image::resize(). Why doesn't it find it?

Question

Yii

Call to undefined method yii\imagine\Image::resize(). Why doesn't it find it?
The documentation says that there is such a method.
www.yiiframework.com/doc-2.0/yii-imagine-baseimage...
Tried again via yii\imagine\BaseImage still the same error.
Here is the code:

$watermark = \yii\imagine\BaseImage::resize(
  $_SERVER["DOCUMENT_ROOT"].'/upload/art-code.png',
  $width
);
$image = Image::watermark(
  $image,
  $watermark,
  [0,0]
)->save($savePath);

Answer 1

You need to update the version of the imagine/imagine library.

Answer 2

Most likely the php gd add-on is not installed.