Tone Reproduction for Realistic Computer Generated Images
Tumblin, John Erwin (Jack)
Rushmeier, Holly E.
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Radiosity and other global illumination methods for image synthesis calculate the 'real world' radiance values of a scene instead of the display radiance values that will represent them. Ad-hoc conversions cause serious errors, and give little assurance that the evoked visual sensations are truly equivalent. Photographers devised sensation matching methods as 'tone reproduction' using subjective judgments well suited to film; these were adopted in turn by television and ocmputer graphics systems with little change. We advocate the use of better tone reproduction for computer graphics, using mathematical models of human observers to define an explicit conversion from real-world radiance to display device inputs. Film and television reproduction is summarized, and an example observer model is derived from the brightness vs. luminance functions of Stevens and Stevens. With a brief discussion of shortcomings, we build a crude tone reproduction operator for black and white images. The new operator is demonstrated as a plausible solution to display range problems, and extensions are suggested.