HDR Tools and Definitions
John J. McCann, Alessandro Rizzi · 2011
This chapter introduces the definitions and vocabulary used in the text. We have the technology to study each scene as arrays of millions of pixels. Dynamic range describes the useful range of light. We need to describe the major terms used to describe the measurement of light. We use radiometry to measure electromagnetic radiation (physics); and photometry to standardize human response to light (psychophysics). Dynamic ranges characterize the light reproduction values between the most and least response for each RGB channel, for each media. In psychophysics, the chapter observes complex responses of the human visual system to the number of photons. The use of photometric standards is helpful in describing stimuli and improving communication among authors. However, in human vision there is no simple, precise, determinative relationship between measured light at a pixel and appearance. It requires considerable information on the spatial content of the image to predict appearance. Controlled Vocabulary Terms colorimeters; colorimetry; electromagnetic waves; photometry; radiometry; spatial filters