When enabling gd support in ezpublish in the backoffice administration, :

• images does not display for datatypes images in editing + preview
• impossible to edit images (crop...)

Ajax call to image editing says:
Notice: Undefined variable: hasImageMagick in extension/ezie/classes/image_converter.php on line 57

One idead of fix is:
Add the following in extension/ezie/classes/image_converter.php on line 28:
$hasImageMagick = $hasGD2 = false;

Steps to reproduce

1. Log to admin
2. Preview a content with an image datatype (images does not show)
3. Edit the object (image does not show)
4. Try to edit the image (ajax error)