What does RGB mean ?
RGB means Red Green Blue, ie the primary colors in additive color synthesis. A RGB file consists in composite layers of Red, Gree and Blue, each being coded on 256 levels from 0 to 255. For example, black corresponds to the levels R=0, G=0, B=0, and white corresponds to the levels R=255, G=255, B=255. The RGV system is used by the screens, the scanners and the digital cameras.