Guess a charged-cuppled-device ,CCD, is a part of a digital photograph/image per luminosity; i'm not too attuned to this but thought a CCD was a part of the silver development process...

''In one embodiment, the optical sensor 130 includes charged coupling device (CCD) sensors, whereby image data is sampled by the CCD sensors and is used to better classify the social situation and preprocessing of the optical signal using signal processing techniques can be used to simply classification calculations. For instance, if the CCD sensors detect a low level of light, the mobile device 100 can determine that the mobile device 100 is in a dark location (such as in a pocket, in a room with the lights off, or outside during the night). Whereas if the CCD sensors detect the high level of light, this could indicate that the mobile device 100 is in use or is merely exposed in a room with the lights on or is outside during the daytime. While described in terms of the visible light, the optical sensor 330 could also be a type of camera which detects non-visible light spectra, such as infrared or ultraviolet detectors, or other radiation and energy detectors.''

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