Critical viewing distance

[Richard]

Critical viewing distance is also called CVD.

The HDTV system was designed to increase the field of view to about 30 degrees which requires a larger screen or you sitting closer. At this viewing distance far more detail is required and that is part and parcel of high definition. Both work together in creating the optimal viewing distance that allows you to see detail at the pixel level without being aware of the pixels themselves.

720p uses 1280x720 pixels allowing a critical viewing distance of 3.2 screen heights. If you get any closer you might be able to make out the pixels.

1080i or 1080p uses 1920x1080 pixels with allows a closer critical viewing distance of 2.5 screen heights which also increase the field of vision. The detail response is so fine with 1920x1080 that at 4 screen heights it becomes difficult to make out a 1920x1080 response and at 5 screen heights such a response would appear as a solid field.

Bear in mind these specifications are based on quality HD content which is only guaranteed by a Blu-ray player. You may very well see noise and other artifacts with other sources such as pixelation, contouring, blocking and mosquito noise. It is quite possible that SD content may be a common source for you in which case such a close viewing distance and the broadcast delivery system will make the low resolution and noise painfully obvious. In such cases it is not uncommon to use a longer viewing distance that provides a happy medium such as 5-6 screen heights.

Keep It Simple
If you aren’t going to sit close enough to resolve the resolution of HD then don’t concern yourself over 720p versus 1080p and detail response issues. On the other hand, depending on what size you are looking at, 1080p may be your only choice.

FAQ: 720p versus 1080p

In depth discussion
Viewing Distance