The term 'computer graphics' refers to anything involved in the creation or manipulation of images on a computer, including animated images.

Pixels and the Screen

An image on a computer screen is made up of pixels – tiny elements arranged in a rectangular grid of rows and columns. Pixels are so small that on high-resolution displays they become essentially invisible.

At any given time, each pixel can show only one colour.

Colour Formats

Format Description
24-bit colour Each colour is specified by three 8-bit numbers representing levels of red, green and blue (RGB)
Grayscale Each pixel is a shade of gray, specified by one number on a black-to-white scale; typically 256 shades
Indexed colour A numbered list of possible colours; each pixel's colour is specified by an integer giving its position in the list

The Frame Buffer

The colour values for all pixels on the screen are stored in a large block of memory called the frame buffer.

How it works:

  1. Colour values are changed in the frame buffer;
  2. The screen is redrawn many times per second;
  3. The pixel colours on screen update to match (abbinare) the frame buffer almost immediately.

This model is the basis of raster graphics.

Raster Graphics vs Vector Graphics

Raster Graphics