Remember those old film cameras? The ones that were the in thing before digital photography came into perspective? They all ran some messy light sensitive film that stored the negative image ready for processing. Its size and quality determined the quality of the image. 35mm (the standard frame size) yields better images than a 20mm film.
The era of digital photography replaced this film with a solid-state light sensitive that captures incoming light to create an image. This is the sensor. In essence, the sensor is an integrated circuited printed on a silicon wafer resulting into a pattern with wells. These wells are the pixels we talked about in the previous section. Each pixel (well) is sensitive to light. It will output a figure that is a perfect representation of the light intensity getting onto it.
The more the pixels the higher the image clarity. However, as we have established before, there is a threshold beyond which increasing the megapixel count is next to useless. That aside, the generated light intensity value is then translated an algorithm that is dedicated to creating a high quality image off the raw data.
The sensor is color blind. To generate colors, the sensor needs the help of a mosaic of color filters. There are green, red and blue filters. In this case, each sensor can only receive a specific color information and use it to guess other colors in process known as demosaicing. An alternative approach would be using the Foveon sensor that uses wavelengths to generate color information (different colors have different wavelengths.)
As it would seem, the more the pixels the better. This is a common illusion that stands to be questioned by facts and the iPhone 5S’s impressive 8MP camera. The quality of information generated by a single pixel depends on its size. By making small pixels that fit on a small sensor, you put the detail quality at risk. A bigger pixel can handle noise better hence resulting into a better image. This means that the bigger the sensor the better!
There is more to the image quality than the sensor size. There are different technologies to creating sensors with the most common resulting into the Foveon X3, CCD and CMOS sensors. Each technology has its own benefits.