Seam carving is an image resizing algorithm developed by Shai Avidan and Ariel Shamir. This algorithm alters the dimensions of an image not by scaling or cropping, but rather by intelligently removing pixels from (or adding pixels to) the image that carry little importance.

The importance of a pixel is generally measured by its contrast when compared with its neighbor pixels, but other measures may be used. Additionally, it’s possible to define (or autodetect) areas of high importance (faces, buildings, etc.) in which pixels may not be deleted, and conversely, areas of zero importance which should be removed first. From this information, the algorithm detects seams (continuous lines of pixels joining opposite edges of the image) which have the lowest importance, and deletes those. This shrinks the image by one horizontal or vertical line, depending on which direction the seam ran.

Seam carving can also be run in reverse by adding interpolated pixels along the lowest energy seam.

With this technique, it’s now possible to reduce or enlarge pictures by a wide range, while still retaining details. In normal image scaling, it’s often not possible to scale about factor greater than 2 or less than 0.5, without losing much of the images quality.

More Info : SeamCarving

Check out SeamCarving plugin for GIMP (Examples here)

Optimizing images would always be a tedious task if you are not utilizing a good image processing tool. Certain resizing tools promise that the output images to be optimized, but what they really do is to reduce the clarity of the image and hence its size. But there are certain tools like RIOT, which goes into depths of resampling to perform the actual image optimization.

Optimization with RIOT is very simple. Drag-n-drop the image to be processed onto RIOT and it does everything for you. If you are not satisfied with the default settings, tweak the options available to fine tune further. Use the Resize/Resample option to change the image dimensions and quality.

RIOT Resample

Making RIOT Portable:

Use the method mentioned in this post, to make this application portable so that you can run it directly from your USB Thumb drive.

Features:

• Save and optimize JPEG, GIF and PNG with a simple, clean user interface
• Compress files to desired filesize
• Processing is super fast
• Option to remove metadata (Comments, IPTC, Adobe XMP, EXIF profiles, ICC profiles)
• Resize image by using well known resample filters (ex: Lanczos3, Catmull Rom, Bicubic, and others)
• Adaptive logarithmic tone mapping algorithm (Drago) used for HDR images
• Free and Portable!!!

Download RIOT :

More details at RIOT Homepage