• An image editing software for reference, such as Adobe Photoshop.
  
  

Digital Photography

The term 'digital photography' is used to describe images that have been captured by digital cameras or existing photographs that have been scanned to create digital image data.

The term also describes the processing of digital image data on computers and the output of 'hard copies' or digital prints (on paper or plastic) from this data.

Pixels and Levels

A digital image is one in which the image is constructed from 'pixels' (picture elements) instead of silver halide grains, which is used in conventional photography. Pixels are square and positioned in rows horizontally and vertically to form a grid. Each pixel in the grid is the same size and is uniform in color and brightness, i.e. the tone does not vary from one side of the pixel to the other.

In the illustration below, 10 pixels each with a different tone are used to describe the 'continuous tone' above it. Each different tone is called a 'level' and assigned a numerical value, e.g. 0-9.

The continuous tone of a subject (no steps in brightness)

Ten pixels each with a different tone or level used to describe the above

In a typical digital image there are 256 different levels or separate tones to create a smooth transition from dark to light. If the pixels are sufficiently small when printed out the viewer of the image cannot see the steps in tone thereby giving the lillusion of continuous tone.