Pixiq

Here’s a fact you may not know: the imaging sensor in your camera only records in black and white. Let that sink in for a minute. Each pixel on a digital camera’s imaging chip contains a light-sensitive photodiode that converts light into electrical current in proportion to the quantity of light that falls on it. Photodiodes can’t really tell the difference between different wavelengths of light; they only react to intensity. The typical way to add color to the digital image is to apply a color filter mosaic, using a red-green-blue pattern.

There are several ways to do this, but the most common is by using a filter arranged in what is called a Bayer pattern, which looks like a mosaic of red, green, and blue squares. Half of the total number of pixels are filtered with green (G), while a quarter of the total are filtered with red (R), and the other quarter with blue (B), in a repeating 2x2 arrangement. Rows of color in a sequence of GRGRGR (etc.) alternate with a sequence of BGBGBG. That’s why this output is called sequential RGB (or sRGB). The camera’s processor actually uses the information from the Bayer pattern to interpolate the color of all of the pixels.

In its previous professional-level digital SLRs, such as the S1, S2, and S3, Fuji used a Super CCD SR II chip that has two kinds of photo diodes — shadow (S) and highlight (R). The larger S diodes respond to low light, recording shadow detail, while the R diodes capture highlights at lower sensitivity to retain detail. Fuji claims that this effectively expands the dynamic range beyond what can be achieved with conventional CCDs. In addition to CCD sensors, which used to be really popular but not so much anymore, there are other types used in digital cameras. These include CMOS which is gaining and Foveon sensors, as illustrated here, that are currently used by Sigma cameras.