1. An image-based transaction system comprising: a mobile device image sensor configured to capture image data that represents a face; and an image processing device coupled with the image sensor and configured to: recognize the face as a known target object from a known object database based on features derived from the image data; retrieve target object information from an information indexing system, wherein the target object information is associated with the known target object and an address, and includes an identity of a specific known target object associated with the face; and enable a device to initiate a transaction based on the target object information, using at least one of the address and the identity, wherein the transaction relates to the specific known target object.