bayer filter
CMOS sensors and CCD sensors are sensitive to brightness, but not to color. In order for image sensors to select colors, single- chip digital cameras must filter out light according to primary colors before it hits the photodiodes. In the Bayer filter, named after Eastman Kodak employee Dr. Bryce E. Bayer, a primary color filter, there is an integrated color filter for one of the three primary colors red (R), green (G) or blue (B) in front of each individual pixel.
The raw image of an image sensor with Bayer filter is a grayscale image with Bayer mosaic. The Bayer filter adapts the eye sensitivity curve, which has a much higher sensitivity in the green range than for other colors. For this reason, twice as many pixels are equipped with a green filter than with a red filter and blue filter, with the green filters shifted one pixel line by line. When light falls on the Bayer filter, each pixel converts one of the three primary colors into a voltage. Since natural colors are composed of many hues, depending on the light intensity and hue, the voltage generated will be higher at one pixel and lower at neighboring pixels.
To obtain a realistic image, the color values of the neighboring pixels are included in the calculation of the color values of the central pixel. This is done by interpolation according to a manufacturer-specific algorithm. The final color is obtained by color mixing from the RGB color model. The Bayer pattern somewhat limits the file resolution of the color representation.
Fujifilm has changed the color filter pixel arrangement of the Bayer filter and combines two color filter pixels with the same color next to each other. This allows two adjacent pixels to be combined into one in the CCD sensor. This combining is called pixel binning. The advantage of this technique implemented in the EXR sensor is its higher sensitivity and wider dynamic range compared to other CCD sensors.
The EXR sensor is essentially a switchable image sensor that can adapt its complex electronic behavior to the shooting conditions.