Interactive decoding of machine readable dataforms provides improved control of decoding avoiding inaccurate reading of dataforms. While data is entered (12) and encoded (14) an image of the resulting dataform, such as a data code matrix or two-dimensional bar code, is displayed (16) and continuously updated as the dataform (20) fills with entered data. Using the display (16) and an input unit (12) such as a keyboard, digitizer or scanner, data can be edited to add, modify or delete data while observing the resulting dataform (20). On completion, the final dataform code signals are provided for further use (24) or a copy of the dataform (20) is provided by printing, for example. During decoding, an image of the dataform (20) as captured by a reader (32), such as a laser scanner, CCD matrix or CMOS camera, is displayed (34). Observing the display (34), the operator can determine if the image is too small, out of focus, partially out of view, etc., and take action (33) to improve the reader (32) performance. The dataform (20) is then decoded (36) with improved accuracy and data signals are displayed or printed out (40) or provided for further use (38). Automated image monitoring and reader adjustment is also described. Methods and systems for interactive decoding of dataforms are described.