Image Retargetter

Content-aware image resizing via seam carving. Packed with features to ensure the best possible results and the widest variety of retargettable images, Image Retargetter can intelligently reshape your images without distorting their contents.

What does it do?

Image Retargetting, or "Content Aware Image Resizing" is a term coined by Drs Ariel Shamir and Shai Avidan in defining a process where by images can be stretched or squashed, horizontally or vertically without important parts of the image being distorted.

In simple terms, Image Retargetting allows you to make images wider, narrower, taller or shorter without smooshing up the important details. Normally, if you were to stretch or squeeze a family photograph, the people in the shot would look too wide/tall/thin/short and it'd be obvious to anyone looking at the image that it had been distorted. With Image Retargetting, you can stretch (or shrink) the image, without your distorting your folks out of shape!

An image expanded by the Retargetter

The same image reduced

But, how can it be possible to change the shape of an image without changing the shape of things in the picture and without just cropping the edges off? It seems impossible! The process was defined in a paper presented at SIGGRAPH2007. You can read a PDF copy of the presentation at Dr Shamir's Homepage. There's also an accompanying video on YouTube which'll help explain how the system works, what its limitations are and how the original work might be expanded upon. Retargetting involves locating the edges of objects in the scene, building an energy map that defines the least noticable tracks across the image from one edge to the other and then using that map to carve seams of pixels out of the image (or double them up) in order to change the size of the image without distorting the key features of the scene.

One Size Fits All

When designing for the web, there's always been an issue with the way that text and browser windows can change shape and size but images remain fixed. With the Image Retargetter you can load up and image, fine tune it for the best retargetting results and then export that as a "DynamicScaledImage". This is a tiny Java applet that you drop straight into any page and which'll reshape itself dynamically to fit whatever part of your page design you've put it into.

See here for an amazing, interactive demo!

(You'll need the latest Java-Plugin installed to experience the online demo)

Stretch and Squeeze!

Look at the images below, note how each image shows the whole scene from the original (center) image - no important elements of the scene have been cropped or duplicated and no areas look obviously distorted. Sure, you could do this with PaintShopPro or PhotoShop... but how long would it take? The demo to the right was produced in 2 minutes with the Image Retargetter.

Working with images

The Image Retargetter can work on a variety of images although it's worth noting there are a number of types of image for which this procedure cannot produce useful results. Images where background detail is greater than subject detail; images where foreground objects span from edge to edge of the frame; images where well-defined background objects intersect the subject... for all these and more you'll find it quite difficult to acheive satisfactory results. However, the program comes with a substantial array of pre- and post-processing tricks to help squeeze the best possible results out of the widest variety of original images. You can even draw over the image to dynamically protect areas from seam carving or to remove unwanted seams after analysis.

For many images, all you'll need to do it load them up, select whether you want vertical or horizontal size adjustment and then use the slider bar to stretch them. To get the best results though, and to work with difficult images, making use of the extensive options at the bottom of the screen will be necessary - the detailed, built-in User Guide for explanations of the various options and hints on how to get the best results.

Key Features

• Load, Save and Export
  • Imports GIF, JPEG, PNG and BMP images.
  • Saves in lossless PNG.
  • Export images in the unique DynamicScaledImage applet. This allows you to drop your dynamically resizable image directly into any webpage and have it reshape itself automatically to fit your page design regardless of the users' browser window aspect ratio or size! (See a live demo!)
• Huge array of pre-processing options for edge detection
  • Run in RGB mode, HSL mode, Hue only, Saturation only, Lightness only, reduced colorspace and minimum colorspace.
  • Dynamic scaled edge-preserving smooth function to filter out noise before edge detection.
  • Dynamic scaled edge-enhancer to capture extra detail.
  • Roberts, Sobel, Gaussian, LoG and image segmentation approaches to edge detection help you find the best possible fit for any image.
  • Optional post-blur to correct broken edges in images.
• A variety of manual and automatic pre-analysis protection features to help avoid seams in unwanted parts of the scene
  • Auto-protect skin-tones.
  • Auto-protect bright areas.
  • Auto-protect dark areas.
  • Automatic horizon compensation.
  • Draw directly over the image to brush out protected areas.
• Fast seam analysis
  • Turbo Seam Analysis Mode finds near-optimal seams in a single, ultra-fast pass.
  • Quality Seam Analysis Mode finds the best possible seams in a detailed, multi-pass analysis.
  • Process even huge images quickly by enabling optional data dimension limits: rescales the data without rescaling your image.
• Post-analysis correction features
  • Manually remove any unwanted seam.
  • Draw directly over the image to manually brush out out any group of unwanted seams.
  • Assign your own limits on usable seams to prevent distortion at the extremes of carving.
• Much more!
  • Switch the main display through: Source/Output image, Edge map view, Energy map view, Seam Plot view, Protection Diagnostics view.
  • Detailed help throughout the application.
  • Stylish, modern interface.