uAdaptiveImages is a package that installs and configures the .NET port of the Adaptive Images project for responsive websites.
Once installed, add the macro EnableAdaptiveImages as the first line in your master templates <head> tag. This generates a session cookie for visitors to the site, which tells the server the maximum device width of the browser.
Image requests are re-routed through a handler on the server, which returns the original image for desktop devices but dynamically resizes and returns smaller images for smaller devices such as mobiles and tablets.
The package writes some default configuration options to the web.config file, which you can edit to adjust the behaviour of the package.
See the original project (http://adaptive-images.com/) and the .NET port (https://github.com/davemcdermid/AdaptiveImages) for more information.