The first notable thing about JPEG compression is the way in which the colour of each pixel is stored. Each pixel of the image is assigned 3 bytes to define its colour. All three bytes can have any value from 0 to 255 and every possible combination of the three bytes stands for another colour. In most file formats, the RGB format is used for defining the colour. RGB stands for Red Green Blue. It's named this way because the first of the three bytes tells you how much red there is in the pixel's colour. The second byte tells you how much green there is in the colour and the third byte how much blue. The higher value the first byte has, the more red the pixel looks.