Retina display is just a marketing term coined by Apple that just means that the screen has a higher pixel density. It allows the screen to show more detail and improves the viewing experience. But don’t worry if you don’t have an Apple device, many other devices have high pixel density displays; it’s just that they won’t call it Retina.
ShortPixel Adaptive Images can serve images for Retina displays when the original image have the proper dimensions. Meaning that if you have a Retina counterpart for your original image, or if the original image is big enough, then SPAI will be able to serve it. This makes ShortPixel AI compatible with all the plugins that generate Retina images.
Example 1: If your original image is 600px wide and you have a Macbook with a Retina display (DPI 2x), SPAI will serve a 1200px image only if you previously generated a Retina image.
Example 2: If your original image is 2048px wide, but the placeholder of the image is 551px wide, and you have a high-density display with a DPI of 1.5, SPAI will serve a 827px (551*1.5) version based on the original image.