When you need to alter the proportions of a specific image, you’ve got two basic options at hand; rescaling and cropping. Both of these techniques wield disadvantages along with their respective strengths.
Rescaling stretches, or squeezes the image together, which makes for an unnatural and unappealing result.
Cropping, on the other hand, forces you to reconsider whole sections of the images, leaving out important information and often resulting in barely satisfying pictures.
With the principles of dynamic page layouts in mind, where content automatically rearranges to the window’s size, Shai Avidan and Ariel Shamir developed Seam Carving. This technique, also known as liquid rescaling or -resizing, automatically rearranges the picture’s objects to include everything important in a smaller framing, while retaining the respective dimensions.
How it works
To achieve this, the seam carving algorithm searches for, and eliminates less important parts in the image, using seams. These seams are basically horizontal or vertical running lines, crossing points with a smaller energy function.
Seam Carving also enables the enlargement of images outside their original boundaries, while yet again preserving the picture objects, by calculating and inserting seams in the less important areas.
For a more detailed view on the concept and algorithm, please refer to the above video, or to the Seam Carving website.
Why you should love it
Through Seam Carving, you can change the size of your pictures in any dimension, without distorting the picture’s scene or any elements of it. It’s resizing 3.0, where we’re literally stepping out of the known boundaries.
Also, by assigning additional positive or negative energy values to picture elements, we can not only make sure some things ‘survive’ resizing, but also filter certain parts from the image. This allows easy element elimination, eye appealing results without any learning curve.
Seam Carving Applications
After Seam Carving was first presented, on the SIGGRAPH 2007 conference, developers from all over the world have leaped onto it. The algorithm was implemented in several graphical user interfaces – a.k.a applications.
SEAMonster was the first Seam Carving GUI, developed and released by Michael Swanson, not too long after the initial conference.
The application includes all basic features, like stretching and squashing, forcefully including and removing specific elements. It’s .NET based, so it requires Microsoft .NET Framework Version 2.0.
The Liquid Rescale plugin implements the same features in the GIMP platform. One important difference is that it uses additional layers instead of ‘painting’ the extra energy to preserve or discard elements. You can also further control the intensity of said additional energy.
Contrary to SEAMonster, the plugin is continually being updated. It’s available for Windows and Linux, and can be found here.
Rsizr brings Seam Carving to the web, for all the 2.0ers amongst you. It bundles all major functions in a slick looking flash interface.
This concludes the major Seam Carving players. Several other projects were started that were discontinued, including a photoshop plugin that was sold on to onOne Software and can now be found in their premium suite.
What do you think of Seam Carving? Which application do you prefer, and why? One we missed, perhaps? Don’t be shy, and drop a comment below.