Standard Definition

A Movie DVD contains compressed video at what we refer to as Standard Definition, 480 lines of resolution. DVDs introduced progressive video, which was an improvement over older interlaced signals. Instead of alternating odd and even lines, progressive video presents every line every time. This results in a smoother picture than older television systems were capable of producing.

High Definition

Television has now moved beyond the limits of standard definition. 720p and 1080p dramatically increase the number of pixels displayed on a screen. Screens can display better images, but the medium that distributes the stuff you want to watch lags behind. DVDs are stuck at Standard Definition.

This isn’t the first time that there has been a lag between the ability of a TV to display a better picture and the lack of a medium to store video. VHS (Video Home System), the most popular form of VCR (Video Cassette Recorder)  could only display 240 lines of resolution. I was recently attending a seminar delivered over the course of several weeks, and each week we watched a DVD. There was a problem with the group who had lent the DVDs, and they needed them back. The organizer managed to borrow an alternate copy, but it was a set of VHS tapes. I was amazed at what a difference it made to go back to the old format. Faces were fuzzy and indistinct. I never had a problem with VHS 15 years ago, but once you get accustomed to something better you realize the difference and going back is painful.

The Contenders Vie for the Crown

DVD has not yet been succeeded by another format. HD-DVD and Blu-ray were two new formats that were meant to replace the DVD. One is now defunct, and the other is struggling to gain traction. There is speculation it will never become popular enough to truly replace DVDs. One reason why Blu-ray struggles is that DVDs are really, really inexpensive. This is partly because those who sell DVDs see the end of the line and are rushing to make all the money they can before the gravy train ends. This doesn’t make a whole lot of sense because they’re the same people who want to Blu-ray to take off. Making DVDs dirt cheap changes people’s expectations of what a movie should cost, so the movie industry is shooting itself in the foot.

Fortunately, the people behind Blu-ray have announced plans to lower costs for the new format in the near future to kick-start the transition. Let’s hope that happens.

The Conversion Experience

Upconverting DVD players are the other reason Blu-ray hasn’t taken off. Older DVD players didn’t always look all that great on the new high-resolution screens. This is because the screens are so precise. To illustrate, let’s assume that you have a bar with 4 lights on it. The lights flash according to a pattern. If you want to display that same pattern on a bar that has 8 lights, it’s easy because you just double the pattern, and wherever light number 1 was flashing, both 1 and 2 now flash. Wherever light number 2 was flashing, both 3 and 4 flash, and so on. The pattern translates easily, because it’s just double. But, what if there are only 6 lights? Now, you can’t just double the pattern, you need to make choices about which lights will flash when to best represent the original pattern, but you’ll never get a pattern that identically represents the original pattern because the math doesn’t divide evenly.

One of the great ironies of Digital television is that it is so precise, it shows up flaws. Older, analog TVs could fudge an image and come out looking OK. It is important that that you feed a Digital TV a properly formatted signal so that it displays correctly. The better the TV the better a good signal will look and the worse a bad signal will look. It cuts both ways.

An upconverter improves the way your existing DVD collection looks on your big screen TV. An upconverter doesn’t improve the resolution, it still works from 480 lines of resolution because that’s all that’s available on a DVD, but it takes the original image and stretches it smoothly over the larger space, fudging the numbers to keep things looking smooth, despite the fact that the numbers don’t translate evenly.

To understand the difference, imagine a balloon with words written on it. Before the balloon is blown up, the words are small and clear and you can read them. An old DVD player playing on a big screen TV is kind of like stretching the balloon with your hands to try and make it bigger. The image will be uneven. An upscaler or upconverter stretches the image smoothly, like blowing up the balloon. The even pressure causes each part of the image to be smoothly stretched as the balloon increases in size. It’s still the same image, starting small and stretched big. Nothing new has been added. High definition is like printing in a large font on a piece of paper. There’s no need to stretch the paper image, it’s already as large as the words on the balloon when the balloon is blown up, and it’s going to be a clearer and sharper than the stretched balloon. Even if the balloon has been stetched smoothly by blowing it up, there’s only so much ink to spread out, and it won’t be as crisp and clear as the printed page, but will still be better than stretching by hand.

In addition to smoothly stretching the image, an upconverter can output video via an HDMI cable, which is a digital cable. Older DVD Players are only able to output analog video. This means that the digital signal from the DVD gets converted to analog for the cable, then when it reaches a digital television, it gets converted back into digital. The conversion process to and from analog reduces the quality of the video signal. By using a digital cable, an upconverting DVD player maintains the digital quality of the picture from start to finish, resulting in a better picture, as long as your TV can accept HDMI.

So, an upconverting DVD player provides a smoother, clearer image on a big screen TV by stretching the image smoothly and delivering it to the TV in a digital format.

Why is there an ‘i’ or a ‘p’ on my resolution? That letter at the end of the number refers to whether a television signal is ‘interlaced’ or ‘progressive’. To give a full explanation, I’m going to give you some history. If you’re not interested in the history lesson, all you need to know is that interlaced is lower quality, because it only displays half the screen at a time (odd lines, even lines, odd, even, etc). Progressive does a full screen every time.

Where’s My Ray Gun?

When TVs first came out, they used something called a Cathode Ray Gun to paint dots of light on a glass screen. If you think about an ink-jet printer, it worked something like that but with dots of light shot from inside the TV onto the back of the screen, not drops of ink on a page. That’s why we still call an old style television a ‘CRT’ which stands for Cathode Ray Tube.

There were a lot of challenges for engineers designing the first TV sets to overcome. One of those was that the guns they first built were a little slow. Painting a full screen of dots, the gun had to move really, really fast. It was hard to build guns that would hold up to that kind of speed over a long life span. So, to make it easier on the guns, instead of painting a full screen 60 times per second, they painted two half-screens thirty times each, alternating between the odd lines and the even lines. This meant that the gun didn’t have to move nearly as fast, and they could build more reliable sets with decent picture quality.

Imagine if your inkjet printer worked like that. What if it just painted the odd lines, and then rewound it back to the beginning and printed all the even lines the second time through? It wouldn’t be able to match all those lines up perfectly on the second pass, and you’d get spots where two dots that were supposed to be side by side would be on top of one another or too far apart, resulting in a jagged image. Same with TV. Interlaced images are often jagged. They’re aren’t as clear.

Lacking Upgrade Mobility

It worked, and it was good enough, but the problem is, once you standardize on something, it can be hard to change. Eventually they could build reliable screens that could handle progressive images, but if they switched all the broadcast, cable, and satellite systems to a progressive image, it would mean that all the older televisions would no longer work. If they changed the system, people who just bought a new TV the year before, expecting it to last for 15-20 years would be understandably upset.

The solution, of course, was to build a new televisions that could play both interlaced and progressive signals, and that’s what happened. The first time that people were able to actually get commercial content that was progressive was with DVD players. When DVD players first came out, there were interlaced and progressive models. Today, virtually every DVD player sold will display a progressive signal.

So, old Standard Definition television comes in two flavours, interlaced 480i and progressive 480p. The new higher definition standard 720p does not come in an interlaced variety. The highest level of resolution, 1080, does come in both 1080i and 1080p. This is somewhat confusing, I know.

The reason why 1080 comes in both flavours is that a true 1080p signal is a LOT of information. Broadcast systems and even the cables which run between your TV and other devices simply weren’t able to handle a true HD signal. That’s why all HD broadcasts are still at the time of this writing either 720p or 1080i, not 1080p. The infrastructure to deliver that much information isn’t in place yet and won’t be until TV broadcasters switch to an entirely new system which can handle the new requirements.

The DTV Transition

When that happens, old TVs built before the new standards were in place (March 2007) will stop functioning without a special device to convert the new type of signal into the old type of signal. As of March 2009, anyone in the US who wants to watch TV will need a converter box. In Canada, the transition to all digital isn’t scheduled to happen until 2011. Some countries have already made the transition, and others are on track. You can check your country’s progress on the Wikipedia Digital Television Transition page.

The US first tried to mandate a switch over to all digital years ago, but abandoned the attempt when it became clear what a mess it would be, and extended the deadline several times. The North American television system is complex and involves a lot of different companies working together. I don’t know how things will all work out, but I have two expectations:

1. It’s going to be messy. The system is too big and there are too many cooks in the kitchen for a smooth transition.
2. It’s going to get fixed before too long. There is just too much money at stake for the big companies that run TV to let chaos reign for an extended period of time. The US government has required the change. While big TV companies may have been too lazy to get all the work done in advance (let’s hope I’m being pessimistic), as soon as they start losing money, expeditious action will surely be taken.

Digital

HDMI cables are the best option available for connecting your TV to Disc players, cable boxes, satellite receivers or gaming systems. HDMI stands for High Definition Multimedia Interface. An HDMI cable will carry a 1080p signal and 5.1 surround sound audio together on a single cable, without losing any audio or video quality because the cable is digital.

Digital audio cables transfer audio (not video)  in a digital format. If you have a home theatre system (external speakers), it is best to run a digital audio cable from the television to the stereo system.

Component

Component cables are the second-best option if HDMI is unavailable. These cables are a bundle of five wires that have RCA plugs on the end. RCA plugs are the type that you might use to connect parts of a stereo system together that plug into the little red and white donut-shaped holes on the back of your CD player. The five wires in a component cable are divided into three for video (Red, Green and Blue) and two for audio (usually Red and White). The video wires transfer red, green and blue video signals separately and the audio wires transfer left and right audio. Because the video colours are kept separate, or in components, they produce better images than composite cables, which mix (compose) all three colours into a single signal passed over a single wire.

Composite

Composite is a word used to describe a variety of cables. Coaxial cable is the old style of television cable with the screw-in end that you attached to the back of your TV on the threaded silver post that stuck out the back. RCA cables that had three wires (Red, White and Yellow) passed audio on the red and white wires, while all the video passed through the yellow wire. S-Video had a round plug with four wires positioned inside. All of these cables are called composite, because they combine the three colours into a single wire. They should be avoided if at all possible, because they do not produce as good a picture as the newer styles of cable.

Resolution refers to the number of dots of light on a screen, and says nothing about the size of the screen. Imagine you were bringing a tray of cupcakes to a party. If the only tray you had was a one foot by one foot tray, and you wanted to bring enough cupcakes for 30 people, you’d need to make very small cupcakes to pack them all in. But, if you only had a three foot by two foot tray, and you only wanted to bring 6 cupcakes, the tray would look very sparse. Matching the appropriate size of tray to the number of cupcakes makes for a good presentation. In the same way, you want enough dots of light, or pixels, to be well-spaced on the screen. The larger the screen, the more pixels you need for them to be well spaced. If you pack too many pixels onto too small a screen, the pixels would be too small to be seen from any distance.

Standard Definition

SD, or Standard Definition, is the old type of television, and it has 480 lines of resolution (TV resolution is measured by the number of vertical lines). If we were to measure TV resolution in Megapixels, like we do for digital cameras, standard definition would be 0.3 MP (640×480=307,200 total pixels).  Two new formats have emerged, both of which are considered High Definition, because they are greater than the old Standard Definition. 720 is the equivalent of 0.9 MP and 1080 is the equivalent of 2 MP. High Definition is not a single level of resolution, but simply means anything more than the old standard. That’s why some manufacturers have taken to calling 1080 ‘Full HD’ to try to differentiate it from 720. Of course, they’re going to regret calling it ‘Full HD’ when they decide to make something with higher resolution.

Digital televisions start at 720 lines of resolution, they don’t make them in the old Standard Definition format (at least, not that I’ve ever seen). 1080 screens start at around 40” in size. Why don’t they offer them in smaller sizes? The answer is distance from the screen. TVs are designed to be watched while sitting on a couch 10 feet away.

Getting in Close

When you want to see the detail on a painting in an art gallery, what do you do? You go closer. The closer you are, the better able you are to see the fine detail. From further away, the detail all blends together. You are magnifying the image by getting closer. The same thing happens with TV. The closer you are, the more detail you can see. A 30” television that offered 1080 resolution would be indistinguishable from a 720 television of the same screen size from a distance of ten feet. The dots would have to be so small to be packed into such a small space that you wouldn’t be able to see the fine detail of that image unless you were very close to the screen. You aren’t likely to be watching from that close, so it would be a waste of money to pay for the extra resolution.

The larger a screen is, the easier the detail is to see from further away. The easier it is to see from further away, the better able you are to pick up the fine details on the screen. On a 50” television, 1080 resolution makes a big difference. The screen size is big enough that the pixels are stretched over a large enough area that having the extra resolution really improves the image quality in a noticeable way. Manufacturers still offer 50” screens in 720, and they look OK, but they aren’t ideal and they’re becoming more rare.

Between 40” and 50” its a judgement call whether you want to move to the highest resolution available. 1080 resolution starts at about 40” in screen size and you don’t pay much of a premium for the highest level of resolution at that screen size. The difference at the time of this writing is as little as $100 more for the higher resolution at a 40″ screen size.

Finding the Right Content

To further confuse matters, very little content is available at 1080 resolution. Almost no one broadcasts television at the highest level of resolution. Virtually all cable and satellite television at the time of this writing is 720. So, if you buy a 1080 television, you are essentially future-proofing, getting ready for the day when having the best resolution available will actually matter for main-stream content. Unless you make your own content or you have a Blu-ray or HD-DVD player (more on what that is in a future posting) it doesn’t matter yet what level of HD resolution you have because the companies that deliver content to you have had such a hard time agreeing on how they’re going to deliver high definition video to you.

What’s the Bottom Line?

The bottom line is that if you have a TV below 40” in size, 1080 isn’t really available. For that size 720 is your only option and all you really need. For screens above 40” in size, 1080 will make a difference if you have a video source capable of delivering 1080 resolution to the screen. If your screen is 50” or higher, a 1080 screen is definitely worth spending a little more on.