All I meant was that the typical font is viewed at a much lower resolution than the typical photo (and is obviously composed quite differently), so the aspects of human vision most relevant to the font designers could be quite different from those most relevant to photographers.
Actually the typical font is viewed in a much higher resolution than the typical photo, unless of course you haven't picked up a magazine lately, or watched printed material because the internet is the viewport of preference, and printed material is sooo last century…
I would like to suggest a possibly interesting simple practical experiment for more insight in this discussion:
Create a completely white image, and draw a single horizontal or vertical black "hair-line". (i.e. a single row or column of pixels). Then view this image at 100% magnification on screen. Move back from your screen as far as you can until you can no longer discern the line on screen. (Perhaps try different contrast settings). You could do the same with your printer. At it's highest native resolution, say 1440 dpi, print a single line at that resolution, and see how far away you need to be to avoid the nuisance of seeing a hair in your soup…
Our perception is very sensitive to edges. So much so, that a healthy 25 year old person with good eye-sight, when looking at a quality magazine at arm-length, should easily discern the difference between a font printed from a 1200dpi print-press-plate, or one at 2400dpi.
There is one aspect in all of the discussions about sharpness, resolution, and aliasing, that I miss. I haven't been able to quit find the right words to explain, so my apologies in advance if this seems somewhat Ray-esque:
There is a certain aspect in our perception of images that goes beyond the conscious perception. Those qualities of the reproduction namely that give an image a certain comfortable viewing experience. "Easy on the eyes" so to speak. Compare for example an overprocessed, over-sharpened image, versus a slightly blurry image. Even though the former may have all the measurable characteristics of more apparent sharpness or even real sharpness, the blurry image may still be more pleasing to look at.
Another simple experiment possibly worth a try:
Print a block of text at 300dpi with anti-aliasing.
The softness of the letters should be visible during reading. While the softness can be easily ignored, for some reason reading such a text is far more tiresome than reading sharp text. Which brings me to the example of text on screen 2007 Windows style or Mac style: there may be advantages to not using anti-aliasing to increase apparent micro-contrast useful for reading, but there is also a certain advantage in aligning all horizontals or verticals when appropriate, even at the expense of sharpness, because our eyes/brain will be more comfortable reading/scanning such lines. The question then becomes: How relevant are these trade-offs under certain conditions, specifically for imaging?
Architectural images versus Landscapes?