An image is represented to a computer as a grid of numbers, with each pixel corresponding to a number or set of numbers. For black and white images, each pixel is represented by a single number between 0 and 1, where 0 is black and 1 is white. For color images, each pixel is represented by a set of three numbers for red, green, and blue color values, and the combination of these numbers determines the specific color seen at that pixel. So an image is essentially a numeric representation that a computer can process, with each pixel encoded as a value or set of values.