ISO International Standard

ISO 10505:2009 describes a method for determining the intrinsic root mean square granularity (rms‑granularity) of photographic films. Intrinsic rms-granularity refers to those density fluctuations produced solely by the distribution of developed image forming centres in the photographic emulsion.

Continuous-tone monochrome (silver absorbing species) and colour (dye absorbing species) materials coated on a transmitting support can be measured by the procedures described in ISO 10505:2009. ISO 10505:2009 is intended for imaging systems with viewing magnifications between 5x and 12x (see Annex A).

The following kinds of granularity measurements are not covered by ISO 10505:2009, even though they are photographically important:

• reflecting materials (photographic papers);
• materials having emulsion coated on both sides of the support (e.g. some X-ray films);
• the estimation of the noise power spectrum (Wiener spectrum).