Embodiments of the invention facilitate payment transactions by integrating the image capture and image processing capabilities of certain mobile devices with the card-based payment transaction infrastructure. In some embodiments, a camera contained in a mobile device is used to capture an image of a barcode that is visible on the surface of a substrate. The barcode may represent or otherwise encode one or more of payment account data, consumer authentication data, consumer profile data, or other relevant information. In some embodiments, the captured image may be processed by the mobile device to extract the payment account data, authentication data, or other relevant data. This data may then be communicated to a data processing element that is connected to, or forms part of, a payment processing network in order to conduct the desired payment transaction.