When Auto White Balance (AWB) does not work, photographers resort to manually setting White Balance. The procedure is simple enough: aim the camera at a white sheet of paper, take a color temperature reading and assign that to the color white, and shift all colors accordingly. But how do you do that for a satellite camera taking pictures of Earth?
It just happens that Lake Tuz in southern Turkey dries up in July and August, revealing a bright, pristine white field of salt. The lake’s whiteness is ideal for calibrating the white balance of the cameras on Earth observation satellites.
Lake Tuz is one of eight sites worldwide that can be used as an international reference standard to calibrate and validate satellites’ sensors.[PopSci]