The difference between normal and high-definition TV, for the non-technical among us.

[BelgianMadCow]

20. I should find the formula

here's a good part that explains what I'm on about:

To fully understand the implications of high resolution and high definition vs size, we must first understand something called acuity of vision. The Dictionary of Visual Science defines visual acuity as "acuteness or clearness of vision, especially form vision, which is dependent on the sharpness of the retinal focus within the eye, the sensitivity of the nervous elements, and the interpretative faculty of the brain." What this means is our eyes have a resolution limit. Increased image resolution is simply an technical exercise, beyond our ability to see it, and does not play any part in improving the viewing experience. Our visual acuity is unambiguous and relatively simple to measure.

The most common vision measuring tool is called the Snellen chart. An optometrist will ask you to read from a chart standing 20 feet (or six meters) away from it. The smallets number you can read defines your acuity of vision. This is expressed as a fraction. A normal vision is supposed to be 20/20. 20/10 means that a subject can read, from a distance of twenty feet, the line that a subject with "normal" vision could only read from ten feet. 20/10 vision is therefore twice as good as 20/20. In comparison, 20/40 is twice as bad.

Coming to video display, the human eye’s resolution (acuity) is directly proportional to the size of the elements of the image and inversely proportional to distance from the elements. This relationship is best expressed in degrees.

In simple terms, we can see things that exist within a known angle with the apex being our nose. If you stare straight ahead, you will have a stereoscopic field of view of about 100 degrees, or about 50 degress to the left and right of your nose. We also have a lower limit to our field of view. Scientists express this as an angle as well, but it is less than a degree, and is expressed differently, For angles smaller than 1 degree we use arcminutes and arcseconds as a measurement. An arcminute is equal to one sixtieth (1/60) of one degree. "Normal" visual acuity is considered to be the ability to recognize an optotype (letter on the Snellen chart) when it goes down to 5 minutes of arc. Taking this to displays, the average person cannot see more than two pixels separated by less than 2 arcminutes of angle.

A 42 inch screen is the minimum size, where the pixels are seperated by 2 arcminutes of angle, if you sit some 6 feet away from it. In smaller screens, the pixels are closer. Though they can also display images with 1080p resolutions, the eye will not be able to appreciate that as compared to say 720p even if you sit very near the screen. Both will look the same.

Last comment in this thread: http://www.hifivision.com/television/1604-whats-difference-between-hd-ready-full-hd.html

By the way, plasma is just a technology, and you can have a HD ready or full HD plasma.

Anyway, to each his own, and if you're happy, you're happy. I just question the everlasting tech drive for "more" when we don't use or need it.