Before diving into the technicalities of what is a digital image in photography, it’s important to understand what it is and what its basic characteristics are. For the uninitiated, each pixel in a digital image is simply a small square of color. But when surrounded by pixels of the same color or different colors, these pixels become meaningful when they form a unified whole and make a picture. The success of a digital image depends largely on the way the pixels are used and the process of manipulation.
Digital images consist of a series of rectangular or square pixels. Each pixel represents a specific intensity value and is ordered according to a coordinate system. These data values are then represented by the file size that a computer can store. This information is then interpreted by computer programs to produce a digital representation of the scene. There are several factors that affect the size of the file. Some of them are discussed below. Generally, digital images contain more than one billion pixels.
There are two main types of digital image resolution: lossless and lossy. These two types are largely dependent on the size of the image and the resolution of the computer. The size of a digital image can be specified by its pixels and is commonly referred to as the pixel resolution. For example, a 2000 x 1600 pixel image has a resolution of 3 megapixels. Both are acceptable for printing and web applications.
The resolution of a digital image describes how many pixels the image contains. It is often expressed as a number of pixels across the width and height of the image. For example, a monitor’s resolution of 1280×1024 means that the image is twelve inches wide by ten centimeters tall. More pixels mean higher resolution, but this does not necessarily translate to greater detail. The higher the resolution, the better the quality of the image.
The dynamic range of a digital image is the difference between the darkest tone where a texture cannot be discerned and the lightest tone where a detail can be clearly seen. The dynamic range of a digital image is limited by the number of photons reflected or incident on the photographic paper. The higher the ISO, the lower the dynamic range. Generally, the lower the ISO, the better the image quality will be.
There are many choices in the file format for digital images in photography. However, the most commonly used file formats are JPG, TIF, PNG, and GIF. Each has their own benefits and disadvantages. Here we will cover the basics of each and give you a general idea of which one to use. And remember that you should never compress your images with too much compression. After all, you don’t want your pictures to get blown up and look ugly.