i am getting "Error generating image." Files permission is 777 and gd library is installed I had installed gd library and also given 755 permission to the files but i am getting 500 - error generating issue in my drupal

My site URL is http://vestcom.ca/dev/

One of example URL of error is http://vestcom.ca/dev/?q=sites/default/files/styles/cardealer-car-mini-thumbnail/public/property-photos/IMG_1373.JPG&amp;itok=_DfNUQVW

If anybody have any idea about how do i debug this or how can i get image then please let me know.
Check your image toolkit (URI /admin/config/media/image-toolkit). You must see like this