The invention features a system and method for automatically discriminating between different types of data, such as a barcode and a signature, with an image reader. In brief overview of one embodiment, the automatic discrimination feature of the present image reader allows a human operator to aim a hand-held image reader at a target containing a dataform, a signature, or another data type and actuate the trigger on the image reader. An autodriscrimination module in the image reader in one embodiment analyzes image data representative of the target and determines whether the target contains a dataform, a signature, or another type of data. If the target contains a dataform, the image reader decodes the dataform and outputs decoded dataform data, such as the alphanumeric sequence encoded by a barcode. If the target contains a signature, the image reader captures or stores a representation of the signature.