Originally Posted by bsimpsen
The young lady states that we could argue that "retina display" is more about perceived image quality than specs. But as the specs are based on human visual perception, she's wrong. What you can argue about is viewing distance. Whether that argument will have any effect on sales is another issue entirely.
It's actually a complex area. A number of studies that give us numbers are simply wrong, or limited in their scope. One problem is that most of these studies use white and black. Another very well known study used a green and black monitor.
It should be known that we are most sensitive in the green area of the spectrum, less sensitive in the red, and least sensitive in the blue.. In addition, contrast plays a big part in our ability to see detail.
So a single number isn't really very useful in telling us what we can, or can't see. People tell me that my iPad is very sharp (yes, they are talking about the picture, not the edges). And it is, unless you get too close. But a few things don't always appear sharp. Certain text and graphics can appear aliased. But photos don't. Continuous tone images need less resolution than do hard edge images.
In addition to that, there are sub-pixels. That is, the actual RGB pixels themselves that make up the cluster. They are far smaller than the entire pixel that includes them, and are too small to see on an iPad.
So this issue isn't so cut and dry. I'm willing to bet that the 264ppi screen will appear to be a retina display just about as much as the one on my 4S.