Tags comprising marks arranged in a predetermined pattern are applied to an item. The marks are made with an ink that fluoresces under infrared (IR) light. A camera with a filter acquires an image of the light emitted by the fluorescence of the ink. This image is processed to determine a portion of the image in which the tag is located. Once located, that portion is processed to rectify and align the tag. This rectified image is then processed to read out tag data that is encoded by the arrangement of marks. The tag data may then be used to identify the item, designate shipping information, and so forth.