Instagram has released an update to its iOS application that fires a return salvo at Twitter after the two companies' very public spat. First, Instagram changed the way its photos were shared on Twitter, resulting in them looking cropped in Twitter cards. Then, Twitter blocked Instagram photos from being embedded in tweets entirely.

And it followed that with the rush release of Twitter Photo Filters - a rival in-app retro camera service.

Now, Instagram has responded further by improving its own iPhone, iPod touch and iPad application, adding a new filter - the black and white Willow - and a number of other new features, including improved tilt-shift functionality.

The Instagram app has been slightly redesigned, with a new box next to the shutter button on the camera section. This shows you a preview of the most recent photo in your Camera Roll - a tap takes you there. Those with an iPhone 5 will also see an improved Camera Roll selector.

Speed and reliability have also been improved, and there's now an optional grid to help you frame snaps.

Outside of the camera features, the news feed has been redesigned too and an infinite scroll has been added to user profiles. Filtered photos are now saved in an Instagram folder in the iOS Camera Roll, and there's now a Foursquare button on location pages.

Instagram for Android has also been updated with many of the new features.