ISO 6846:1992 (R2025)

Pertains to all conventional silver-halide contact and enlarging papers used for continuous-tone or pictorial photography. The method is based on exposing and processing samples, performing density measurements from the resultant image to produce a sensitometric curve from which measurements are taken and used to determine ISO speed and ISO range values. Annexes A to C deal with the relationships between the paper range and the effective density range of the negative, log exposure range and contrast, and log exposure range and average gradient.