Dynamic amplification

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Another mechanism involved is still speculation. It assumes that the illumination intensity at the enyzm cascade, which begins as a consequence of pigment decay, directly regulates the amplification of each receptor’s output variables. Scientists have demonstrated a calcium-based process in non-mammalian vertebrate species like turtles, specifically in the outer segment of rod receptors. While this remains speculative for us humans, digital recording technology has already achieved a similar feat. In 1999, researchers from the Fraunhofer Institute for Microelectronic Circuits and Systems developed a sensor chip and a digital camera system that provide good images even with large differences in brightness. The system first reads out each pixel with up to four different exposure times, then selects the most favorable one. In the second step, the chip amplifies the image signals at different levels based on the signal value. The chip increases low levels, such as the shadow areas of an image, while leaving the high levels from the highlight area unchanged. In combination, both methods ensure that overmodulation of the pixels is largely avoided when the brightness is too high. After reading out the image signals, the gain selected by the chip and the corresponding exposure time are added to the digital values. Based on this information, special software then determines the correct brightness value for each pixel. The complete system allows the display of one million different brightness values.

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