It was introduced with the iPhone 4 in June 2010.
What Is Retina Display?
Retina Display smooths the jagged edges of the screen’s pixels and makes images seem more natural.
Apple Studio Display.Apple
The benefits of the technology are particularly visible when looking at text.
On Retina Display, the curved edges of fonts are substantially smoother than on previous display technologies.
This metric is based on a combination of the rig’s screen resolution and its physical size.
The iPhone 4 had 326 PPI due to a 3.5-inch screen with a 960-by-640 resolution.
This spec was the original PPI for all Retina Display screens.
That changed as later models were released.
For example, the iPad Air 2 has a 2048-by-1536 pixel screen, resulting in 264 PPI.
That, too, is a Retina Display screen.
This is where the second factor comes in.
Viewing Distance
Viewing distance refers to how far away users typically hold the equipment from their faces.
Something that’s seen up close needs a greater pixel density for the eye not to see the pixels.
Pixel density can be lower for displays viewed at a greater distance.
These include:
Want to know how a Liquid Retina Display is different from the original Retina Display?
Find outWhat Is a Liquid Retina Display?
