Conclusion: for many of us, current screens are close to perfection…
Not because screens cannot be better – no, far from it. If manufacturer’s can do 5″ 300+ ppi panels, they can do larger 300+ ppi panels. The issue is, introducing that kind of resolutions will perhaps break more stuff than it will fix!
I already knew from experience that I could barely make out a single-pixel wide line on my Dell Ultrasharp U2711, sitting ~2ft/60cm away from it – and that panel is not even at 110 ppi. That instinctively proves the formula, stating that the optimal viewing distance is actually within 10% of what I would consider the minimum “workable” distance – that is a full screen diagonal.
We could easily ask for a 200 or 300ppi 27″, that given the proper hardware would lead to jaw-dropping details in current and future games, or photographers could daydream viewing their high resolution photos from their new D-SLR aided by that premium piece of glass. But for certain graphic design and CAD work, this resolutions could be problematic, before the whole UI and view-port codes were re-written. Simply put, with resolutions that high, any short of fine details around 1-2 pixels wide, would be so small, that leaning backwards even a few inches away from the “optimal” viewing distance, it would would be increasingly harder or even impossible to distinguish it between the wash of light coming from the neighboring pixels – especially in low contrast scenarios.
Apple solved the UI problem, by doubling the ppi resolution of its old panel, or quadrupling the pixel count: effectively each pixel of the UI is interpolated to four, using a simple code that can scale up older UI that were written in times when such resolutions would be unheard of. Think of it as FSAA, only the graphic engine is not sizing down the final result. They could do a bigger ppi panel and get it – but the above trick would not be possible unless it was in full integer multiples from the original, forcing them to ask for everybody to redevelop their UIs in order for the rMBP to have app menus and buttons that are still visible!
But what about the content within the UI? What about the times we don’t want to lose the tree in the forest? Well, we have a long way to go. For sure a good start would be the standardization of a fully scalable UI system, that would allow us increasing the resolution without shrinking the control buttons and menus to levels that we cannot distinguish.
Till then, be happy with what is already available. Unless it is a 27″ 1080p !