This International Standard describes the calibration of test sets that perform end-face image analysis, also known as near-field or grey-scale analysis. The principles, however, may be applied to test sets of a different type. The procedures outlined are to be performed by calibration laboratories and by the manufacturers or users of geometry test sets, for the purpose of calibrating geometry test sets and for evaluating the uncertainties in measurements made on calibrated test sets. The calibration of fibre coating or cable measurement test sets is not covered by this standard.