Pixels Per Inch
Pixels Per Inch (PPI) is a measurement of pixel density that expresses how many pixels are contained within one linear inch of a display or digital image. It is calculated by dividing the total number of pixels along one dimension by the physical size in inches along that same dimension. Higher PPI values indicate greater pixel density, which generally results in sharper, more detailed visual output when viewed at typical distances.
Display and Imaging Applications
PPI is commonly used as a specification for digital displays, including computer monitors, smartphones, and televisions. In this context, it determines the sharpness of the image rendered on the screen. A higher PPI means individual pixels are smaller and less visible to the human eye, creating a smoother appearance. This metric is particularly critical for mobile devices where viewing distance is short, necessitating high density to prevent the “screen door effect.”
Distinction from DPI
PPI is often confused with Dots Per Inch (DPI), but the terms refer to different processes. PPI applies to digital images and screens, describing the resolution of the source file or the physical pixel grid of a display. DPI, conversely, is a measure used in printing, indicating how many ink dots a printer places per inch on physical media. While a high PPI image can produce a high-quality print, the final output quality also depends on the printer’s DPI capability and the paper type.