Thanks to Mark Maunder for picking this up: the content aware image resizing algorithm I wrote up has been productized as a website called RSizr.com and as a Gimp plugin called Liquid Rescale.

Below are some screenshots showing Rsizr.com in action.

I took a shot of some elephants and painted them with the proection brush in Resizr to discourage the algorithm from eliminating them in the seams– it turns out that the algorithm thinks that dull grey elephants are pretty “uninteresting” compared with the speckled water.

 Here is a before and after shot showing the retargeted picture, the algorithm did a good job. All essential details are preserved with no visible seams, with only a small amount of manual effort to protect the elephants. (Cropping would not have worked well here because the elephants fill the frame.)

Rsizr can also remove pieces of the picture do you don’t want, treating them as regions of no energy in the seam finding algorithm.  Here I retargeted the image to remove the middle elephant.  Close inspection shows a visible seam in the water but it’s still pretty impressive.