Minimum Distance for Retina Effect

Eric Rucker, DisplayBlog reader, in response to HTC Sensation 4G where I suggested using the 256-ppi Sensation 4G from a distance of more than 12 inches to get the Retina effect:

If I recall correctly, the definition is a display that exceeds the average human’s ability to resolve individual pixels. Therefore, a display need not be 326 ppi to be a retina display at 12″ – in fact, with 20/20 vision, 286.5 is the magic number.

Rucker also developed a neat JavaScript Display Calculator that gives you: aspect ratio, ppi, minimum Retina viewing distance, etc. According to Rucker’s Calculator to get the Retina effect on the iPhone 4 you need to use it from at least 10.4 inches assuming you have 20/20 vision. For the Sensation 4G the distance is at least 13.4 inches.