In U.S. broadcast television, there are a two basic TV video display methods: progressive scan and interlaced.

Interlaced means the lines that make up the picture on your TV screen are drawn in an alternating fashion. In the U.S., first the even lines appear on the screen, then the odd lines appear. Standard TV is interlaced. This is the TV format we've all been watching since television was invented.

Progressive scan means the lines that make up the TV picture are displayed all at once in sequence. HDTVs are capable of at least 1280x720p ('p' for progressive scan). While they can also accept an interlaced signal, they natively display progressive scan video.

Progressive scan DVD players are capable of 720x480p, and the newer upscaling DVD players and high def DVD players are capable of up to 1080p depending on the model (see the TechDigs.net article Want Better DVD Movies? Buy an Upconverting Player!).

Without getting into the gory details, the interlaced method was originally used because CRT technology in early TVs wasn't fast enough to keep up with a progressive scan of approximately 480 lines. It could, however, keep up with 240 lines. Therefore, standard U.S. TV broadcasts first send the even 240 lines, and then the odd 240 lines.

The problem with interlacing technology is this alternating line drawing tends to cause the eyes to see a flicker. Unfortunately, interlacing reared its ugly head again in the 1990s when established HDTV standards included both 720p and 1080i options. Some broadcast networks use 1280x720p (720 lines progressively displayed) and some use 1920x1080i (540 even lines drawn, then 540 odd lines drawn). As of 2006, no U.S. broadcast network uses 1080p, or 'full HD' (1920x1080p).

The problem with 1080i is that despite having more total lines, it generally doesn't look as good as 720p. This is especially true for high-motion video such as sports. If you have a large (over 46") HDTV hooked up properly and want to see an example of this, watch a punt return on HDTV NBC Sunday Night Football, and then watch a punt return on HDTV Monday Night ESPN Football. The difference is significant. With far less aliasing (visible chunky pixels), ESPN's 1280x720p looks substantially better than NBC's 1920x1080i. While some of this may be due to the compression used by NBC or the cable outlet, most of it is due to interlacing.

If you have an HDTV, how can you get the best progressive scan picture?

1. Properly connect your devices.
   Make sure both your DVD and HDTV set-top box are connected optimally. If you don't use at least a component video cable for both, you won't see progressive video or HDTV resolutions. For more on this, see the TechDigs.net article, Get the Right Video Connection on Your HDTV .
2. Use the correct DVD player.
   Spend the money to get, at minimum, a progressive scan DVD player. A basic progressive scan DVD player can be purchased for less than $50. If you want even better quality, your dollars are better spent on an upconverting DVD player. Starting at less than $200, these newer DVD players upscale 480p DVD content even higher. For more details, see a recent TechDigs.net article, Want Better DVD Movies? Buy an Upconverting Player!
3. Fixing broadcast TV.
   Other than watching more HDTV (especially 720p) than standard TV, there's not much you can do. You have no choice in the broadcast format you receive. While there are some video scalers and processors available that help clean up interlaced signals, most of them are still too expensive to justify the cost.
   

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cameron said:

i want HDTV

December 12, 2006

tv watcher said:

I just want a cheap analog to digital signal converter.

December 14, 2006

CHON CHON said:

thanks for the info ive been looking at HDTVS and was confused about the difference between I and P.

January 08, 2007

e.t. said:

if i have a tv with component inputs (edtv) should it matter what kind of component cables i use; i.e interlaced or progressive?

February 26, 2007

TechDigs.net said:

e.t.: Component cables are the same whether for interlaced or progressive. Unless you are going very long distances, don't get caught up in getting the most expensive cables. It won't pay off -- especially at EDTV resolutions. We like Monoprice cables (http://www.monoprice.com/products/subdepartment.asp?c_id=102&cp_id=10235&style=). In general, however, I wouldn't get RG-59, instead get RG-6/18 guage. For 6 feet, you should be able to do that for $15 or less.

February 27, 2007

Samuel Smith said:

Great review ... Thanks for the info !!!

March 06, 2007

muslim said:

thanks a lot for this great review Now the diffrents is very clear so we can tlak to people as experts allah bless you, lead you to more deeper worlds.

June 13, 2007

the badger said:

so are you stating that, a tv with progressive i.e. 1080p is more future proof than interlaced i.e. 1080i.................. buy a p not an i this is how i read it... thanks

July 09, 2007

Jason said:

Hi, I just bought a PS3 mostly for it blu-ray technology and was wondering what setting is better for watching movies. My tv is a plasma capable of both 720p and 1080i. In all honestly i don't see a huge difference between either but I would like it to be set in the bust resolution. Thanks

December 05, 2007

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