The use of scanners to provide digital image files is rapidly growing. Currently there is no standardized method to determine the dynamic range of scanners. Therefore the data reported in technical specifications can be determined using different methods. An ISO 21550 Standard to measure the ability of scanners to reproduce tones especially in the dark areas of the original is currently under development (in an early working draft stage). At the present time most of the manufacturers report the dynamic range calculated from the bit depth of the implemented A/D conversion using the formula