Pixel values represent the colour and how bright a specific pixel in an image is. Pixel value varies according to certain images. Binary images only need a 1-bit number stored for every pixel (black or white) whereas gray scale images have pixel values of only one number to indicate t he amount of gray needed (0 – black to 255 – white)
In an RGB colourspace the values of a pixel sum down to three separate numbers (red, green and blue) ranging from 0-255 referring to how bright the colour will be. These three values are usually stored as three different gray scale images (colour planes) and are later combined together when being displayed or processed.