If you have configured the fileformat setting in the configuration file to save images as TIFF - Group IV files, you must scan documents bi-tonally (that is, in black and white) because the TIFF - Group IV file format does not support grayscale or color images.
If your scanner is configured to scan in color or grayscale and you are attempting to scan documents using a TIFF - Group IV file format, the fileformat setting is ignored and documents are saved using the JPEG file format.