Two-parameter gloss methods

Abstract

Th e co ncep t of a parameter of gloss iness, t hat is, measurem ent und er one set of illum inat in g a nd view in g co nditions, is developed. T o d es cribe comp letely t he g l os~i ness of a sp ecime n r eq uires mul l ipara met ri c meas ureme nts o n t he geometri c di stribut ion of r eflected li g ht-fiu x. As o ne-para met!" r methods ha ve bee n fo und to y ield in a deq uate descripti ons of specimen glossin ess, two-param eter methods were in vesti gated . For specimens \\'it h differin g in cid pnce-angle dependell cy, a two-par a meter method u sin g s pec ular gloss meas urements at two in cid e nce angles is s uggested . For s pecimens with differin g flu x-scatteri ng characte ristics, a two-param eter method usin g s pec ul a r gloss measur em ent s for two r eccptor apertures is s ugges ted . Several ex istin g stan da rd h vo-pa ra.m eter met hods ar c r e v iewed. R esults of a seven-labora to ry rou nd -rob in test of the t wo-paramet er (receptor a perture) method a re r ep orted a nd a na ly zed . To estab lis h co rrelat ion between m easurements obta in ed with t he s ugges ted two-par a meter (rece pt or apert ure) method and s ubjective e valuatio n of image brightness and _ image di stinctness, a s ubjective test was formul ated . Th e r es ults of t hi s test, here a na ly zC'd an d di scussC'd , indi cate t he usefuln ess of t he t \\'o-paramctC' r Ill e thod .