Seam carving allows an image to be resized non-uniformly, so you can change the height to width ratio in the image without cropping, but also without distorting important features in the image (such as faces).
A rather geeky/technical weblog, est. 2001, by Bramus
Seam carving allows an image to be resized non-uniformly, so you can change the height to width ratio in the image without cropping, but also without distorting important features in the image (such as faces).