Creating safety protocols

Creating safety protocols

The image formation process within an imaging system, be it a human eye or a digital camera, is dependent on three factors: the physical properties of the imaged surfaces -referred to as reflectances-, the light incident upon those surfaces and the characteris- tics of the imaging system. In general, numerical measurements made by the imaging system do not allow for the subsequent dissociation of these factors: i.e., given an image without additional information, one cannot invert that process and explicitly separate re- flectance, illumination and the characteristics of the system. The problem of separating illumination from reflectance is often referred to as the colour constancy problem.

The importance of solving for colour constancy is illustrated by the fact that a colour signal captured by an imaging system is the combination of surface reflectance proper- ties and illumination conditions. The difficulty lies in the variety of possible illuminants, since even commonly encountered ones have very different spectral properties. Fig. 2.1 shows the same scene pictured under three standard illuminants: sky light, neon light and tungsten light -a common light bulb. One can see that, despite the reflectances in the scenes being identical, the colours in the images vary significantly and, as illustrated

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