System and method for scene light source analysis

Claim 1

A system for analysis of a scene light source to which a light sensitive medium is to be exposed comprising: a) spectral measurement means for measuring spectral intensities of said light source at predetermined increments of wavelength in each of a plurality of colors; b) data storage means for providing reference spectral data at corresponding increments of wavelength for each of said plurality of colors, said reference spectral data being representative of (i) spectral transmittances of a plurality of known filter types, (ii) spectral sensitivities of said light sensitive medium, and (iii) spectral intensities of a reference illuminant on which said light sensitive medium spectral sensitivities are based; c) a microcomputer; and d) an output display device; e) the microcomputer being programmed to respond to said reference spectral data and to said measured light source spectral intensities in each of said colors for determining (i) first log exposures of said light sensitive medium to said light source (ii) second log exposures of said light sensitive medium to said reference illuminant (iii) differences between said first and second log exposures and (iv) an error value comprised of a summation of the absolute values of said differences, said microcomputer being further programmed to be responsive to said error value (v) to make a selection from said known filter types that provides a desired approximation of spectral response of the light sensitive material to the light source relative to the spectral response of the material to the reference illuminant, and (vi) for providing said selection to said output display device for presentation to a user of said system.

Claim 2

A system for analysis of a scene light source to which a light sensitive medium is to be exposed comprising: a) spectral measurement means for measuring spectral intensities of said light source at predetermined increments of wavelength in each of a plurality of colors; b) data storage means for providing reference spectral data at corresponding increments of wavelength for each of said plurality of colors, said reference spectral data being representative of (i) spectral transmittances of a plurality of known filter types, (ii) spectral sensitivities of said light sensitive medium, and (iii) spectral intensities of a reference illuminant on which said light sensitive medium spectral sensitivities are based; c) a microcomputer; and d) an output display device; e) the microcomputer being programmed to respond to said reference spectral data and to said measured light source spectral intensities in each of said colors for determining (i) first log exposures of said light sensitive medium to said light source (ii) second log exposures of said light sensitive medium to said reference illuminant (iii) differences between said first and second log exposures and (iv) an error value comprised of a summation of the absolute values of said differences, said microcomputer being further programmed to be responsive to said error value (v) to make a selection from said known filter types that provides a desired approximation of spectral response of the light sensitive material to the light source relative to the spectral response of the material to the reference illuminant, and (vi) for providing said selection to said output display device for presentation to a user of said system.

Claim 4

A method of analyzing a light source for exposure to a light sensitive medium, comprising the steps of: providing spectral sensitivity data for a known light sensitive medium; providing spectral intensity data for a reference illuminant intended for the light sensitive medium; measuring spectral intensity of said light source at predetermined increments of wavelength; determining log exposures for the measured light source for each of a plurality of colors as a function of the integral of the product, at incremental wavelengths, of measured light source spectral intensities and spectral sensitivities of said known light sensitive medium; determining log exposures for the reference illuminant for each of said plurality of colors as a function of the integral of the product, at said incremental wavelengths, of reference illuminant spectral intensities and spectral sensitivities of said known light sensitive medium; determining, for each of said colors, log exposure difference values between the log exposures of the measured light source and the reference illuminant; and displaying said determined difference values on a sensitometric curve display for said known light sensitive medium.

Claim 5

A method of analyzing a light source for exposure to a light sensitive medium, comprising the steps of: providing spectral sensitivity data for a known light sensitive medium; providing spectral intensity data for a reference illuminant intended for the light sensitive medium; measuring spectral intensity of said light source at predetermined increments of wavelength; determining log exposures for the measured light source for each of a plurality of colors as a function of the integral of the product, at incremental wavelengths, of measured light source spectral intensities and spectral sensitivities of said known light sensitive medium; determining log exposures for the reference illuminant for each of said plurality of colors as a function of the integral of the product, at said incremental wavelengths, of reference illuminant spectral intensities and spectral sensitivities of said known light sensitive medium; determining, for each of said colors, log exposure difference values between the log exposures of the measured light source and the reference illuminant; and displaying said determined difference values on a sensitometric curve display for said known light sensitive medium.