background header image page breadcrumbs

Hello,

I am using the (updated) Petz theme and I want to change the image (standard jumbotron.jpg i.e. 1600x667) of the background image for the page breadcrumbs in designer. The new image is exactly the same format as the jumbotron.jpg which comes with the design package, yet I can not cut out the needed part of that image to be displayed. I also tried to place the new image within the same dir as the jumbotron.jpg, renamed it to jumbotron.jpg but all fails into the same problem. See examples of image selected and result.

Any suggestions on this? Also, what is the size of the selection displayed when you want to cut out and can an image of that size directly be used in that format size or will it be blown up too?