How will Font Rasterization and Sub pixel rendering be affected with the new retina displays?
If you go to the Accessibility control panel, you can enable a zoom mode that blows up whatever is being displayed. Using this, you can detect subpixel antialiasing because it shows up as color fringes when magnified.
I tried this out and found that, yes, the Retina MacBook Pro does still use sub-pixel antialiasing (when LCD font smoothing is on).
Somewhat surprisingly, it's even still on if you're using a scaled resolution! If you use virtual 1680x1050 mode, the computer writes everything to a 3360x2100 buffer and then scales it down to the 2880x1800 of the display, which of course means any subpixel antialiasing doesn't actually make sense any more (since it'd get interpolated to colors that don't necessarily match the subpixel locations any more..)
You'd think this would create weird color fringing artifacts. However, fact is, the resolution is so ridiculously high that I can't tell at all. Maybe if I had a physical magnifying glass....
A Retina display is a screen with a high pixel density. Apple's marketing material defines it like so:
The pixel density is so high, your eyes can’t discern individual pixels.
But at a technical level, the Retina displays on the iPhone, iPod, iPad and MacBook Pro are exactly double the pixel density of the non-Retina models. This is because scaling to an exact multiple solves many issues that can occur if you're scaling to a fractional size.
In terms of sub-pixel text rendering, OS X uses it for the Retina MacBook Pro in all cases where it's possible.
- If the text is being drawn onto an opaque background.
- If "Use LCD font smoothing when available" is turned on in System Preferences.
- If the display is the normal orientation.
The last point is an important one. iOS caters for all orientations, so the OS can't assume the sub-pixel order of the display. This is the main reason why iOS doesn't have sub-pixel text rendering.
Even on a high pixel density display, there is an advantage to using sub-pixel rendering, and OS X uses it where possible.
The simple answer is that the Retina display looks great, but doesn't change the method text is rendered.
At this order of resolution (meant as in ppi) one can drop subpixel rendering altogether without making much of a difference (difference will be almost unnoticable if at all visible). I think even hinting could be dropped and almost no harm will be done. So much pixels on an inch of length implies rather “printwise” mindset instead of traditional “displaywise” one.
Besides, I think all “retina” talk nowadays should be more “about time” than “wow” :). The need and idea are quite old. The same are potential benefits and technical possibilities. It's all really “at last” kind of thing ;).