Image sensors have a more or less high light sensitivity depending on their size and the number of pixels. To increase this and reduce the associated image noise, some image sensor manufacturers have developed special technologies for the highest possible light yield. Fujitsu's EXR sensor is one such CCD sensor with optimized light yield, and the Foveon X3 sensor is another.
The development of the EXR sensor is based on the consideration that the sharpness-critical lines for luminance, i.e. brightness perception, are highest at an angle of 45 degrees. For this reason, the scanning grid of the pixel elements in the EXR sensor is rotated by 45 degrees compared to the horizontal arrangement. The arrangement of the photodiodes also had the advantage that the pixels are closer together than in a horizontal arrangement. This results in lower image noise and thus an improved signal-to-noise (S/N) ratio. The color filter used always assigns two pixels of the same color to each other and thus has a different arrangement than the Bayer filter. This makes it easier to combine neighboring pixels by means of binning.
In front of the color filter, the EXR sensor still has a microlens system that focuses the amount of light on the respective pixel. The EXR sensor has twice as many green pixels as red or blue. This is due to the fact that eye sensitivity is highest in the green area.