| OCR Text |
Show 84 energy E. The transformation from a numerical value to a a complex task, because it involves several systems: the electronics of the the phosphor of the cathode the As eye. ray tube and the of these none systems scope, of subjective brightness perception linear, it is are is subjective brightness then necessary to define a function which can transform numerical data into brightness levels. Among the non-linearities synthetic image. the only of the of non-linearity mathematically formulated; therefore for this systems involved in the generation of technique a the film cannot be photographic has been a developed to compensate non-linearity (Stockham [31 ]). The cathode ray tube phosphor - radiated by striking the the is screen a This screen. can be chosen so that the intensity light linear function of the energy of the electron beam the therefore energy, intensity, 'light be can approximated by the following function: - I where d is light on a constant, = relation between n vcvo )iGamma vo is the excitation vc is the actual excitation the screen, and Knowing the d*( power Gamma, and the radiated is it light to voltage corresponding then an absence of voltage. possible energy L to by using produce a a compensation linear table ' for this value of Gamma. Assuming that with the a now that the non-linearity Gamma table, In most of the cases, Gamma is about .33. of phosphor the z-axix of the amplifier screen of the CRT of the scope can it is then desired that the reflectance (or is be linear and compensated transmittance in |
