Reliable Reflection Density Measurement.

The densitometer instrument is a mainstay of control of the process of producing printed materials from the time of initiation of the image to the final product. However, it is well known that the data obtained from various instruments cannot be interchanged or expected to be accurate in the sense that data from any given instrument is correct. Those who use densitometry have routinely observed the caution that only one instrument is used for a given condition to obtain comparable density. This report is based on a study that has shown that the precaution of using a single instrument need not be observed if the basis of the data is spectrophotometric measurement calibrated in terms of absolute reflectance with density values calculated according to procedures described in appropriate ANSI standards. Further information is given on the various instrument calibration standards with the recommendation of a more reliable universal standard which can be used for calibrating densitometers of any manufacture.