Pixel density is a term used to refer to the number of pixels, or picture elements, present within a given space in a number of different contexts. The term is often used with reference to monitors and television screens to indicate the quality of the screen at various resolutions. It can also be used when dealing with image scanners and digital cameras to refer to how well an image can be captured based on the number of pixels in an area that can be scanned. Pixel density can also be used in reference to printers and printing images, regarding the number of individual pixels printed in a given space.
Often measured in pixels per inch (PPI), pixel density is typically demonstrated with reference to a given amount of area, often a single inch (2.54 cm). Pixel density indicates how many picture elements, each a tiny point of light or color that makes up an image, are present within that space. The higher the number, the greater the image quality, as more pixels in a space allow for greater resolution of an image and higher detail.
On a computer monitor or television screen, for example, the pixel density often indicates how many pixels exist in a given space on the screen. Each pixel on a screen is a single tiny “dot” of light that makes up the large image displayed on the screen; these individual pixels can often be viewed when looking very closely at a screen. With higher numbers of pixels, and greater pixel density, these individual dots are harder to see and more seamlessly create an overall image.
Computer scanners and digital cameras often also provide a numeric pixel density to indicate the quality of the image that can be captured or scanned. Higher numbers indicate greater image clarity and detail, as greater numbers of pixels can ensure a cleaner image. A scanner with low density, for example, could scan a photograph in a way that is somewhat “blocky” and lacks the smoothness of the original image.
Pixel density is typically used to indicate the quality of a printer as well. In print, each pixel is an individual dot of ink or toner used to create the overall image, similar to the artistic style of pointillism. Printers with greater density can print more dots within a given space, and therefore create a smoother image with greater detail. This is often important for commercial printers used in printing magazines, in which photographs and images are displayed at high resolutions.