In the TV world, there is nothing that has been debated more than 720p vs. 1080p. There are those who insisted that there was very little in the way of 1080p content, or that the human eye could not resolve the added detail with ease. Turns out, the answer is much easier: The question isn’t about 1080p vs 720p, it’s whether or not your TV has 1080i 3:2 inverse telecine.
Myth #1: There’s very little 1080p content
Fact: There is a ton of 1080p content available.
Every scripted TV show or movie broadcast (i.e. non-reality-show, non-sporting-event) on CBS, NBC, CW, HBO, Showtime, InHD, TNT, Discovery, and Universal can be viewed in 1080p. Although the transmission format is 1080i60, TVs or video cards with content-based 3:2 inverse telecine have the ability to take the 1080i60 and reconstruct the original 1080p frames at 24 frames per second. This isn’t mathematical magic or interpolation – the real 1080p data is there. It just needs to be decoded. Of course, both HD DVD and Blu-ray are recorded with 1080 lines of resolution.
When it comes to 720p sources, you have ABC, FOX, ESPN and of course, most Xbox 360 and PS3 games. The question then becomes, what type of TV will give me the best picture for the majority of content? To figure this out, we need to think about the 4 different TVs.
Scenario 1: 1080p TV without 3:2 inverse telecine
Without inverse telecine, the original 1080p signal cannot be reconstructed from the 1080i broadcasts. That means that as much as half of the resolution is thrown away! The 1920x1080i is “effectively” converted to 1920x540p. For 720p broadcasts, the television has to upscale from 720p to 1080p. Some TVs will scale better than others.
1080i content: Bad
720p content: OK
Scenario 2: 720p TV without 3:2 inverse telecine
Just as above, the lack of inverse telecine becomes a problem. The 1920x1080i broadcast is converted to 1920x540. From that point, you scale 1920x540 to 1280x720. Again, when you scale the image, it can introduce artifacts. However, in this case, there is no processing that needs to happen when displaying 720p images.
1080i content: Bad
720p content: Perfect
Scenario 3: 1080p TV with 3:2 inverse telecine.
With inverse telecine, you get all of detail you were meant to see with 1080i content. The reconstruction happens “perfectly” as if you were watching a 720p broadcast on a 720p display. There’s not wizardy involved – you’re just tapping into the quality that’s hidden in the source. In general, TVs with HD inverse telecine have a good enough scaler where you can go from 720p to 1080p reasonably.
1080i content: Almost Perfect* (we’ll get to this)
720p content: Good.
Scenario 4: 720p TV with 3:2 inverse telecine.
With inverse telecine, you have to downscale 1920x1080 to 1280x720. This can still introduce artifacts, but you’re starting off with more pixels and that helps to keep the quality up. In contrast,
1080i content: Good
720p content: Perfect.
What are the artifacts of scaling? Going from 1280x720p typically generates a slightly “blurrier” picture. After all, you’re working with fewer pixels to begin with. Importantly, if you sit back “far enough” from the TV, the blurriness isn’t a problem – you’re already beyond the limit of human vision. In general, the artifacts that occur when going from 1080p to 720p usually show up as jaggies. These artifacts are particularly visible in motion, and because the eye is tuned for “local contrast,” we feel that these artifacts are more glaring when compared side by side.
So from a purely technical standpoint, it makes sense to go with a video processor that can do 3:2 inverse telecine and for technical reasons, upsampling 720p to 1080p tends to produce fewer artifacts than downscaling 1080p to 720p. Don’t forget that the quality of the scaler makes a difference – a high-end scaler can do 1080p down to 720p with few artifacts (but it can also go from 720p to 1080p with few artifacts as well).
FiringSquad Recommendation #1: Your video processor needs 3:2 inverse telecine
As long as you have inverse telecine, you will be able to enjoy the optimal resolution for the majority of film-based content. When it comes to deinterlacing 1080i60 to 1080p60 for sporting events, awards shows, documentaries, you start to get into the more complex question of which TVs do a good job of 1080i60 deinterlacing and which TVs throw away as much as half of the information. We’ll have to leave that discussion to a future article.