@prefix isq: <https://w3id.org/standards/isq/ontologies/core/> .
@prefix smart: <https://example.org/smart-sdu/> .
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix dcterms: <http://purl.org/dc/terms/> .
@prefix skos: <http://www.w3.org/2004/02/skos/core#> .

<isq:t7-26.2>
  a isq:Entry ;
  rdf:type isq:Quantity ;
  rdf:type smart:TermEntry ;
  dcterms:identifier "7-26.2" ;
  skosxl:prefLabel "tristimulus values for the CIE 1964 standard colorimetric observer"@en ;
  skosxl:altLabel "X_(10), Y_(10), Z_(10)"@en ;
  skos:definition "amounts of the three reference colour stimuli in the CIE 1964 standard colorimetric system, required to match the colour of the stimulus considered"@en ;
  smart:hasBindingnessType "bindingness-type:normative" ;
  dcterms:isPartOf <isq:part-7> ;
  isq:hasUnit [
    skos:notation stem:["see Remark"] ;
    skosxl:prefLabel "see Remark"@en
  ] ;
  skos:note "For a given colour stimulus described by the colour stimulus function stem:[varphi_lambda(lambda)] of a radiometric quantity,\n\n[stem%unnumbered]\n++++\nX_(10) = k int_0^(oo) varphi_lambda(lambda) bar x_(10) (lambda) \"d\"lambda\n++++\n\n[stem%unnumbered]\n++++\nY_(10) = k int_0^(oo) varphi_lambda(lambda) bar y_(10) (lambda) \"d\"lambda\n++++\n\n[stem%unnumbered]\n++++\nZ_(10) = k int_0^(oo) varphi_lambda(lambda) bar z_(10) (lambda) \"d\"lambda\n++++\n\nwhere stem:[bar x_(10)(lambda)], stem:[bar y_(10)(lambda)], stem:[bar z_(10)(lambda)] are the CIE colour-matching functions for the CIE 1964 standard colorimetric observer (10&deg; observer) (<<t7-27.2>>).\n\nFor sources, stem:[k] may be chosen as stem:[k = K_(10)] where stem:[K_(10)] is the maximum luminous efficacy (<<t7-11.3>>) of the CIE 1964 standard colorimetric observer so that stem:[Y_(10) = L_(10)] and the unit of stem:[X], stem:[Y], stem:[Z] is [stem:[\"unitsml(cd*m^(-2))\"]].\n\nFor object colours, stem:[varphi_lambda(lambda)] is given by one of the three products\n\n[stem%unnumbered]\n++++\nvarphi_lambda (lambda) = S_lambda (lambda) * {(rho(lambda)),(tau(lambda)),(beta(lambda)):}\n++++\n\nwhere stem:[S_lambda(lambda)] is the relative spectral distribution of a quantity characterizing the source illuminating the object, stem:[rho(lambda)] is the spectral reflectance, stem:[tau(lambda)] is the spectral transmittance, stem:[beta(lambda)] is the spectral radiance factor, and stem:[k] is chosen to be\n\n[stem%unnumbered]\n++++\nk = 100 // int_0^(oo) S_lambda (lambda) bar y (lambda) \"d\"lambda\n++++\n\nIntegral limits can be confined depending on the spectral sensitivity of the detectors used as a sensor. In this case, the unit of stem:[X], stem:[Y], stem:[Z] is [1].\n"@en ;
  iso:urn <urn:iso:std:iso:80000:-7:ed-2:en:item:7-26.2> .