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Image Sensors

A digital image sensor is an integrate circuit used for measuring light intensity. Image sensors have become ubiquitous over the last decade, finding their way into phones, computers, digital cameras, and automobiles. Film has been made all but obsolete due to the advances in image sensor technology.
The two key image sensor technologies are charge-coupled devices (CCD) and complementary metal-oxide-semiconductor (CMOS). Although they were both created a roughly the same time, CCD images dominated the market for many years due to superior image quality. As fabrication technology improved, CMOS imagers eventually became a viable option. Today, CMOS imagers dominate the low-cost consumer electronics space, whereas CCDs still provide exceptional image quality but at the cost of speed.
There are several important image sensor specifications to consider. The number of pixels captured is typically given in megapixels. Pixel counts can range dramatically from sensor to sensor. Pixel size refers to the area on the sensor dedicated to each pixel. Larger pixel areas can receive more photons and therefore typically provide cleaner, less noisy images. Note that for a given sensor size, increasing the pixel count decreases pixel area and vice versa. Another important aspect of image sensors is how they capture color information: a single-chip sensor uses a Bayer filter to capture only red, green, or blue at each pixel. A three-chip camera captures RGB at every pixel.
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