Determining Lightness from an Image

A 111ct11od l i ~ r t h e tic-termination ol' liglntness t'rom image intensity is prcscwtc~l . 1;or certain classes ot' images, l i g l ~ t r ~ e s s corresponds to rcflrctancc, whilc~ irni~ge intc*nsity is the product ol' rcflcctance :und illr~mination intensity. T l ~ e mct l~ot l is twot l i~nc~ls io~ni~ l :und clcpends o n t l ~ c liffercwt spntid tlistril)r~tion of tllesctwo cornp)nrn ts ol' innage illtensity. SIICII i~ ligl1t1less-jl1dgi11g process is r e q ~ ~ i r e d for L m d ' s r ~ t i n e x t l ~ c w y 01' color vision. A numl)er of p11ysic;d models a r c tlcwelopetl and connputer silnr~lation ol' t h e process is tle~iionstratcd. T l ~ i s work s h o r ~ l d I I ~ of interest to tlesigncrs 01' imagc* proccwing Ili~rd\wircI, cognitive psycl~ologists cl( : i~l i~~g wit11 the humiun visr~nl system ~ I I I C I n e ~ ~ r o ~ ) l ~ y s i o l o g i s t s concerned with the l'unction of s t r u c t ~ ~ r c s in t l ~ c primates re tin;^.