It is possible to create Instagram-like filter effects using just JavaScript. You can leverage an existing library, such as Filterous (https://github.com/girliemac/Filterous), to modify the image canvas directly.
There is an Instagram plugin (https://github.com/vstirbu/InstagramPlugin) for Cordova on GitHub. You could write some extra code to pass the image to Instagram. The user must have Instagram installed on the phone first, though. This idea is nice when you plan to do some cool image processing (for example, adding funny text) before letting Instagram perform the photo filter operation.
You could even add the Cordova's social network plugin and post the resulting images to Twitter or Facebook.
