Abstract: The present invention relates to scanning multi-sided documents. The scanner device scans the multi-sided document one side at a time. The image of each side is tiled vertically or horizontally to form a composite image, which is transferred from the source to the application based on the TWAIN protocol. The source is TWAIN compliant, and it allows any TWAIN application to scan and process multi-sided cards as a single composite image. The source provides a TWAIN user interface which allows the user to select scanning parameters and options. The invention also provides a method of implementing a TWAIN source to use the document sensor on a scanner to efficiently scan single or multi-sided cards based on the TWAIN protocol. The source checks the status of the document sensor when the TWAIN user interface is displayed, and automatically starts scanning when a document is detected by the sensor.