This is something that is discussed in depth within the full Digital Intermediate paper found within this website, but here is something you might like to try for yourself.

The following image shows a standard approach to assessing resolution using 'lines' of information.

This additional image shows the exactly the same 'resolution' but using a crosshatch pattern.

Interesting, isn't it? The crosshatch image appears to have a much finer resolution, which I guess it does as it has vertical resolution as well as horizontal while the 'lines' image only has horizontal. In the real world any image has vertical as well as horizontal, so which is a better judge of the human reaction to an image and its resolution?

If you print these images and cover an entire A4 (letter for USA readers) sized piece of paper with them, replicating the images as necessary, you will have the equivalent sized pixel based image as for a 2K digital projector projecting onto on a 30ft screen (a pixel roughly one sixth of an inch square - the actual figure is 5.6888 pixels per inch).

When viewed from a distance of 24ft (a 30ft screen showing a 1.85 image has a screen height of roughly 16ft, so 1.5 times screen height, which is an optimal viewing distance =24ft and subtends a horizontal width of 64 degrees, well beyond the 'optimal' 30 to 45 degrees) the image containing lines will still be 'visible' as your eye will tell you there is a pattern there, even if you can't actually see it in detail.

However, the crosshatch image will become completely grey with no discernible detail or pixels at the same distance. What is the most amazing is the distance at which the crosshatch pattern becomes indistinguishable from total grey...

So, the question is, what is the real resolution that the human eye can define?

For more in-depth information please review the "Technical Papers" within the links at the top of this page.