Photographie and Sound health

CMOS sensors and their grids of photodiodes operate something like CCD imagers in the sense that each photo site can be compared to a bucket that fills with photons that are directed onto the photosensitive area by a micro lens. However, a CMOS sensor photo site contains lots of circuitry not found in a CCD photo site and so there is less room for the photosensitive area. In some CMOS sensors, the sensitive area may be about 50 percent of the total area of each photo site. The same thresholds and bucket-filling analogies apply to how CMOS captures photons. However, unlike CCD chips, the electrons are converted to digital form right within the individual photosets. Circuitry converts the photons to electrons (as in a CCD imager) but then transforms the charge into an amplified voltage value. CMOS sensors can include a kind of pixel-resetting circuitry to, more or less, bleed off excessive photons before they can overflow to the adjacent pixels. So, CMOS chips are much, much less prone to blooming effects. The whole process is more efficient, because all the signal processing can be handled in parallel and with less energy consumption. “Sweeping” the image off the chip by rows and columns isn’t necessary. Every photo site on a CMOS imager can be accessed directly. The circuitry found in a CMOS imager is basically similar to that in standard chips such as RAM, so CMOS sensors can be produced using the same equipment and production lines, in contrast to CCD chips which require special fabrication methods. So, CMOS sensors can be relatively inexpensive compared to CCD on a pixel-by-pixel basis. On the other hand, the smaller photosensitive area of these chips makes it more difficult to produce high-quality images, and the resulting sensors are less sensitive to light, too.