LqR plugin in action
A video of a simple rescaling example, made with the previous version 0.4 of the plugin:
Here you can find some simple examples of what can be obtained using the LqR plugin.
Click on the pictures to see the full-size versions.
The second image was obtained by setting “140%” in the “Width” field.
The girl (♥) had to be “protected” from deformation using a preservation mask.
Element removal example
The second image was obtained by successively removing image elements (by shrinking with discard masks), and then by liquid-rescaling back to the original size.
Note that, depending on the picture and the desired result, other techniques, such as using the Resynthesizer GIMP plugin, can yield better results.
Combining more than one technique is a good idea, too.
Content enhancement example
The second image was obtained by shrinking the image with LqR in a uniform way, but using protective masks for the girl (♥) and for the Alhambra palace in background, then using standard scale to go back to the original size. This procedure was iterated twice. The result is that of a “smart” zoom of image elements.
There's a collection of pictures on Flickr made using the LqR plugin; you can see a slide-show below.
Note, however, that some of them use more filters than just LqR, some were made with previous versions, some aim at distorting the pictures, etc.
Go to the Flickr page if you want to see how they were made and how the original images looked.
The algorithm explained
The video below was made by the original algorithm creators, and presented at SIGGRAPH 2007.
It explains the purpose and the principles of “liquid rescaling” (seam carving).
The plugin currently allows doing all that is shown here (and something more), now including the real-time resizing, (which however is only possible after the first image processing, i.e. after you have rescaled it at least once).