Definition of ‘PPI (Pixels Per Inch)’
A measure of the resolution, or clarity, of a video display. The higher the number of pixels per inch, or PPI, the more detail the screen will convey.
Investopedia explains ‘PPI (Pixels Per Inch)’
Each pixel on the display of a smartphone, computer screen or television is a tiny representation of part of the original image. The greater the density of pixels, the more accurately the video screen will reproduce the overall image.
While pixel density is one of the most important factors when it comes to image clarity, it’s not the only contributor. For example, the type of screen technology, such as LCD or OLED, can also play a role in how vivid the picture appears.
When calculating the number of pixels per inch, the size of the display is an important consideration. A high-definition television labeled “720p” – in other words having 1280 pixels horizontally and 720 pixels vertically – would have more pixels per inch if the screen is relatively small. For this reason, larger devices require more pixels to maintain the same image clarity as smaller monitors.
At a certain point, the limits of the human eye make it impossible to notice the difference created by a greater pixel density, especially at a distance. For example, when Apple introduced the 326 PPI “Retina” screen on its iPhone 4, the company claimed that it reached the maximum perceivable resolution at normal viewing distances.
Since the advent of smartphones, screen manufacturers have struggled to develop products with greater pixel density than the competition. With many iPhone and other displays now surpassing the limits of human vision, however, other criteria may play an even greater role in building market share going forward. In particular, companies are competing to develop better screen technologies that most accurately replicate the original image.