What is a Digital Image?

A digital photo is made up of a series of pixels (picture elements). Most of today’s digital photos use a “24-bit RGB” system to color each pixel.

When using digital equipment to capture, store, modify and view photographic images, they must first be converted to a set of numbers in a process called digitization or scanning. Computers are very good at storing and manipulating numbers, so once your image has been digitized you can use your computer to archive, examine, alter, display, transmit, or print your photographs in an incredible variety of ways.

Pixels

Digital images are composed of pixels (short for picture elements). Each pixel represents the color (or grey level for black and white photos) at a single point in the image, so a pixel is like a tiny dot of a particular color. By measuring the color of an image at a large number of points, we can create a digital approximation of the image from which a copy of the original can be reconstructed. Pixels are a little like grain particles in a conventional photographic image, but arranged in a regular pattern of rows and columns and store information somewhat differently.

Types of Digital Images

For photographic purposes, there are two important types of digital images— color and black and white. Colour images are made up of colored pixels while black and white images are made of pixels in different shades of grey.

Resolution

The density of pixels in an image is referred to as its resolution. The higher the resolution, the more information the image contains. If we keep the image size the same and increase the resolution, the image gets sharper and more detailed. Alternatively, with a higher resolution image, we can produce a larger image with the same amount of detail.