Terminology The term specific intensity is used in the classic works on radiation such as Planck 1914 and many other authoritative physics texts That was the reason for introducing this article that reason has nothing to do with computer graphics The classic authorities actually speak of specific intensity without the qualifier radiative because they are writing in a radiative context As for seniority one could ask seniority of what Seniority of Wikipedia entry or seniority of material Does the Wikipedia have a policy of authority for seniority of Wikipedia entry The term specific intensity is over a century old The term radiance is an update improvement promulgated by authority of committees and is the product of committees Paltridge and PlattPaltridge G W Platt C M R 1976 Radiative Processes in Meteorology and Climatology Elsevier Amsterdam page 35 a reliable source in its field comment Even basic quantities such as radiant flux and radiant intensity as used in the general literature are not often the same as the formally endorsed definitions of those terms So far as I understand it the function of the Wikipedia is to collect and report and make accessible findings from reliable sources which are many and various in this case So far as I understand it it is not to act as a thought police to enforce exclusive conformity the recommendations of committees which are only one kind of reliable source and not to try to regulate diversity of viewpoint and not to try to enforce conformity to the one and only true and correct and errorless and completely general doctrine and point of view and form of language According to Born and Wolf Born M 1999 Principles of Optics seventh edition reprinted 2003 Cambridge University Press Cambridge UK page 194 a reliable source in its field and to HapkeHapke B 1993 Theory of Reflectance and Emittance Spectroscopy Cambridge University Press Cambridge UK page 64 also a reliable source in its field the terms spectral brightness and specific intensity and spectral radiance mean the same thing They refer to a field quantity per unit frequency or wavelength per unit area per unit solid angles They refer to a fileld of non collimated light They are different from irradiance and from light intensity which both have the dimension of energy flux density per unit area Intensity refers to a beam of collimated light Irradiance refers to non collimated light immediately originating from a specified surface per unit area of view from a specified direction The reason for the qualifier specific is to make the term apply to uncollimated non blackbody radiation as well as to blackbody radiation and to provide for solid angle The term light intensity by itself is sometimes Born and Wolf 1999 used to refer to the intensity of a collimated beam This is also called the irradiance The specific intensity of a thermal radiative field is non zero because it is per unit solid angle while the integral flux in any exactly specified direction is infinitesimal and unmeasurable as such The intensity of a collimated beam is not infinitesimal and is measurable as such because it is in the exactly specified direction of the beam Born and Wolf comment It is unfortunate that the same word is used to denote two different quantities The term brightness is currently defined in its Wikipedia article with the source given as the ordinary language dictionary of Webster A different definition is given in the Oxford English dictionary but is not cited by the Wikipedia article No opinion is offered by that Wikipedia article as to the relative reliabilities of those two sources The Wikipedia article on brightness currently does not have much to say about brightness referring to specific radiative intensity apart from offering opinions about what is correct according to the US government In the latter opinion it seems from the Wikipedia article that brightness is currently opined as a term of psychophysics not of the physics of matter Perhaps someone will feel like remedying this As for specificity for light the terms discussed in the present articles in general refer to all wavelengths of electromagnetic radiation not just to the visible wavelengths Some authors regard the term light as referring to all wavelengths not only to the visible References