ANSI IT2 37:2001 pdf download.Photography -Print Grain Index -Assessment of Print Graininess from Color Negative Film.
ANSI IT2 37describes a method for determining the Print Grain Index (PGI) of a uniform neutral color photographic print made from an unmodulated neutral exposure of a color negative film.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this American National Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this American National Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards.
ANSIII3A 1T2.40-2003, Root Mean Square (rms) Granularity of Fl/in (Images On One Side Only) — Method for Measuring
ANSI/ISO 2721:1982 (R1997), ANSI/PIMA 1T3.301-1990 (R1997), Photography
— Cameras — Automatic controls of exposure
ANSI/PIMA 12.39-1998, Photography — Black-and-white, continuous-tone films
— Photographic modulation transfer function
ISO 5-3: 1 995, Photography — Density measurements — Part 3: Spectral conditions
3 Terms and definitions
For the purposes of this standard, the following terms and definitions apply.
3.1 graininess: Sensation produced. in the mind of an observer viewing a photographic image, by random inhomogeneity in what should he structureless areas.
NOTE 1: Graininess is, therefore, a subjective quantity that is measured by psychophysical methods.
NOTE 2: Above threshold, the just-noticeable difference in graininess detectable by observers viewing uniform areas having an ISO visual density of about 1 .0 corresponds to a difference in rmsgranularity of 6% in monochrome materials
3.2 microdensity: Transform of the rnicrotransmittance factor in accordance with the relation.
3.3 microtransmittance factor: Transmittance factor of a small area of the film or paper measured on a suitable instrument such as a microdensitometer or microphotometer.
NOTE I: In general. the rnicrotransrnittance factor of a uniformly exposed and developed film or paper sample varies from point-to- point on the sample.
NOTE 2: The measured microtransmittance factor of a given sample may depend on the optical geometry of the instrument with which it is measured.
3.4 print grain index (PGI): A perceptually uniform scale (above threshold) that correlates with the graininess of a uniform color photographic print as perceived by an observer.
NOTE: PGI is calculated for a specified film printed at a specified magnification.
3.5 rms-granularity: Objective characterization of the spatial microdensity fluctuations in a uniformly exposed and developed photographic layer
NOTE: The spatial fluctuation is observed when the microdensity of the layer is measured at various points over the surface and is the result of the random distribution of the absorbent species in the layer.ANSI IT2 37 pdf download.