Is there a ceiling for how high-definition televisions can get?

Picture this: you have two movie copies and two TVs. One is on Blu-ray with a high-definition television (HDTV), while the other is on a standard DVD with a standard-definition TV. You sync both videos and observe the results.

The image difference between the two setups will be clear. The HDTV should deliver a sharper picture with richer colors than the standard model. Have we reached the ultimate video quality, or is there more to come?

When we refer to HDTVs, we’re really discussing the image resolution. A television screen is made up of millions of tiny light dots known as pixels. Standard-definition TVs have a resolution of 480, meaning there are around 480 horizontal lines running from the top to the bottom of the screen that generate the images you see.

High-definition TVs have more pixel lines to form images. The low end of the high-definition standard in the U.S. consists of about 720 lines of pixels, while the high end includes approximately 1,080 lines. Manufacturers are gradually replacing the 720-line models with the 1,080-line ones.

Using additional pixels to form an image results in a smoother picture. Imagine being given a stack of green and brown paper squares, and your task is to create an image of a tree. If the squares are large, the tree will appear blocky with jagged edges. But with smaller squares, the tree will appear smoother and more realistic.

That’s the role of high-definition television. It’s not only about the number of pixels, but also about the size of each individual pixel. As you increase the number of pixels on a screen, the pixels themselves must become smaller. This leads to the creation of smoother images.

But is 1080p the ultimate resolution? Could you buy a TV with even more packed pixels? Would it truly make a difference? And would you be able to find content that supports the higher resolution? Let’s explore.

Fitting More Pixels on HDTV Screens

At present, the highest resolution TV available in the United States is 1080 lines. This isn't due to a physical limit on pixel capacity, but rather because of the HDTV standard. While many high-definition TVs can upscale standard signals to match their resolution, true high-definition content is essential for the full experience.

High-definition video is accessible via certain cable or satellite services, a Blu-ray or HD-DVD player, or a variety of devices such as the PlayStation 3 or Xbox 360. This content will appear sharper than upscaled standard-definition content on an HDTV. If a manufacturer released a TV with more pixels, it wouldn't make much of a difference without compatible content from providers.

On smaller screens, a higher resolution may not be necessary. This is because the number of pixels on HDTVs remains constant, regardless of screen size. It’s a balance of pixels versus area. A 720-line HDTV has 1,280 vertical lines and 720 horizontal lines, totaling 921,600 pixels. Meanwhile, a 1080-line HDTV has 1,920 vertical lines and 1,080 horizontal lines, totaling 2,073,600 pixels.

Generally, all 1080-line HDTVs have the same pixel count. Whether your TV has a 26-inch (about 66 cm) or a 55-inch (about 140 cm) diagonal, it will still display 2,073,600 pixels. The pixels on the smaller 26-inch screen will simply be smaller.

But do smaller pixels actually improve the picture? If you place a 26-inch HDTV with 720p resolution next to a 26-inch HDTV with 1080p resolution, you might not notice a difference. The pixels in a 720p display are already so small that making them smaller doesn't enhance the picture quality.

For larger screens — 55 inches (around 140 centimeters) or more — the 1080p resolution is ideal. That's because bigger screens use larger pixels. If the pixels are too large, the image can look jagged or blocky. The distance between the screen and your eyes also plays a role: the further away you are, the smoother the image will seem.

Giant Televisions

As televisions get larger, more pixels are needed to produce a smooth image. For most homes, a 1080p resolution should be sufficient. However, if you have a mansion and are looking for a 200-inch (508-centimeter) television for your living room, 1080p will not be enough. The unfortunate reality is that even if you own a television with a vast number of pixels, you might not find content that matches that resolution.

In the future, ultra-high definition televisions (UHDTVs) may become more common. While the highest resolution for HDTVs in the United States is 1,080 horizontal lines, the UHDTV standard could reach closer to 4,000 lines. A 200-inch television with 4,000 lines of resolution could deliver the crisp, smooth images desired in such a massive screen.

Some manufacturers are already developing technology capable of creating UHDTV content. One example is the RED ONE camera, which can record at 4,000 lines of resolution at 30 frames per second. The RED ONE's output isn't specifically designed for televisions but for filmmakers creating HD movies for cinema. By the way, the RED ONE captures images made up of 12,065,000 pixels [source: Red.com].

Again, cramming that many pixels into a smaller television won’t necessarily result in a noticeably better image. However, for giant screens and movie theaters, it's essential. You need each pixel to be tiny in order to create high-definition images.

The limits of HDTV are not really determined by technology, but by human biology. If a person can't distinguish between a 26-inch (66-centimeter) screen with fewer than 1,000,000 pixels and one with 12,065,000 pixels, there's little reason to push the technology beyond that point. For most consumers, a 1080p resolution will likely be sufficient. As with many things in life, more isn't always better.