An image-based transaction system includes a mobile device with an image sensor that is programmed to capture, via the image sensor, a digital images of a scene. The mobile device identifies a document using image characteristics from the captured images and acquires an image of at least a part of the document, and then identifies symbols in the image based on locations within the image of the document. The symbols can include alphanumeric symbols. The mobile device processes the symbols according to their type to obtain an address related to the document and the symbols and initiates a transaction associated with the identified document.