Whats the difference between HD "Interlaced" and "Progressive" and which is better.?

Question

Whats the difference between HD "Interlaced" and "Progressive" and which is better.?

Answer 1

Lets explain it in this example.

1080p HDTV will draw 1080 vertical lines of resolution at a time so you are viewing 1080 HD.

1080i HDTV will draw 540 odd, then 540 even vertical lines of resolution, then interlace (combine) to trick the eye into thinking it sees 1080 lines of resolution.

so 480p is a true 480 where as 480i is 240 odd, and 240 even Interlaced at a very high speed so the eye sees 480 lines. Progressive is a more true resolution than interlaced but interlaced is not bad if it's a high resolution like 1080i it will look very good but not as good as 1080p.

Now that explained, in the USA the transmission standards do not support 1080p so if you get a 720p HDTV and you just want to watch HDTV your set. a 720p HDTV will display 480i,480p,720p,1080i just fine only leaving you to have to downscale 1080p so it's fine for HDTV viewing. 1080p in the USA at present is only available on Blue-Ray players (including PS3) and some HD-DVD players (dieing out).

I hope this was helpful.

Answer 2

As mentioned before the difference is that interlaced shows half the lines at once even numbered and then odd numbered lines while progressive shows all the lines at once.

Progressive is better since interlaced will in most cases give you jagged edges and screen flicker.

Answer 3

I've been wondering this myself, and from everything I've read I'm less than convinced about the reigning wisdom.

Everyone seems to be concentrating on the fact that interlaced only displays half the resolution at a time, implying that therefore the resolutions isn't "true".

I think people are missing the point that (considering 1080i) there is still a genuine 1080 lines of detail (just like 1080p). The difference is that instead of drawing them all in one hit, it staggers the picture over two passes.

Why do this? If you consider a non-real world example of an animation at 1fps (just to keep numbers simpler). Consider the first scenario of flashing a picture in front of your eyes for an instant (it appears to linger longer on the retina), before jumping forward to the next picture set 1 second later. This would be progressive.

Now, the alternative system is to split that image in two – so still the same amount of detail – and stagger it so there are two images flashed per second. Except in this case the second image contains the action between the two other frames. Effectively the frame rate is doubled, and the eye can make a smoother transition between what would have been twice the gap between frames.

So in summary, interlaced video has the same resolution on the screen but it is delivered in two parts, causing there to be less of a jump between full frames.

I suspect the reason people consider progressive to be higher quality is when they freeze-frame and see progressive to be a nice quality picture, while interlaced images have the "jaggy" effect. But still frames aren't what video was created for.

So if someone could point out a fault in the logic above, please let me know. Otherwise, I'd love someone to enlighten me on why conventional wisdom is that progressive is better.

Answer 4

Amazon.com has a link called "High-Def 101" where they discuss all the ins and outs of HDTV.  According to the link, progressive is better.  Not exactly sure why, but the gist I got from the article is interlaced works on the same principle as a standard picture tube (random use of signals and light waves), while progressive reads the code in sequence and transmits the picture accordingly.  At any rate, they claim the best HDTV you can get is a 1080p, which is progressive HD with 1080 lines of resolution (as opposed to 720 in some HDTVs or 480 max on a standard TV).

Answer 5

In a nutshell:

Interlaced means the lines that make up the picture on your TV screen are drawn in an alternating fashion.

Progressive scan means the lines that make up the TV picture are displayed all at once in sequence.

I think Progressive is better because "The problem with interlacing technology is this alternating line drawing tends to cause the eyes to see a flicker"...quoted from the website under my sources below this.