Should you upgrade to a HD (High Definition) TV?

These days one is bombarded with adverts for the latest flat, widescreen, HD (high definition) TV. If you go into the shops that sell these TVs, the images you see on them are truly amazing. The colours and clarity are spectacular and it’s pretty hard not to be impressed. So impressed that you might just splash out for that new 103cm HDTV.

Boy, that great picture would look mighty good installed on your living room wall – or would it?


Samsung HDTV

Samsung HDTV

Well depending on what you like to watch and how fussy you are about your picture quality, you may be very disappointed.

The reason is that the majority of TV channels in South Africa are still broadcast in SD (Standard Definition) and, very unfortunately, HDTVs don’t do a great job of displaying SD signals on a HD screen. And the larger the TV, the worse it looks! To be fair, let me quickly add that if you are, however, watching a full HD Blu-ray movie or an HD channel off your satellite decoder, the picture on most HDTVs will indeed look excellent. Those demos you see in the shops have been very carefully filmed to look the very best on an HDTV.

Without giving a long lecture on the matter, most SD screens have 720 pixels across and 480 lines down, while most full HDTV screens have 1920 pixels across and 1080 lines down. So when you feed an SD channels into an HDTV, it has to try its best to fit the SD pixels into the HD pixels. One would think that since there are so many more, much smaller, pixels in the HD screen, that this wouldn’t be that hard. Well it turns out that it is pretty hard, and HDTVs don’t succeed very well.

The process of converting SD video to display on a HD screen is called upscaling and all HDTVs have some form of upscaling mechanism built-in but, in my opinion, they are an afterthought by the TV manufacturers – something they have to have. If you don’t believe me, go into a shop and ask them to switch their top-end HDTV to a non-HD channel, say SuperSport 1. Every time I’ve done this, the picture I see is a poor second to watching SuperSport 1 back at home my existing SDTV picture.

The difficulty in matching the SD pixels with the HD pixels comes wherever the image is not a straight line, which is obviously most of the time. As soon as there is a curve or a line that changes in shape, the upscaler has to ‘guess’ where to fill in the HD pixels to match that shape. This leads to something called “negative artifacts”, which (in very basic terms) are pixels that show something they shouldn’t. When the upscaler gets this wrong, you get a less-than-perfect picture. Take a look at the images of the roses below. It shows how the image quality of the original can be reduced after going through an upscaler. This is an exaggerated example, but is useful to show the concept.


A rose before and after upscaling

A rose before and after upscaling

So there is a whole additional industry out there that can sell you “good” upscalers, that claim to upgrade nearly any signal to full HD with much better results. These specialised upscalers can be found in DVD players, home theater systems (e.g. Onkyo has something called Qdeo Technology) and as standalone gadgets like the DVDO Edge. Even the HD satellite decoder from DSTV has a built-in upscaler of sorts. By all accounts i.e. those from expert and consumer forums, these upscalers produce less-than-satisfactory results.

Most of the channels I watch on TV are still broadcast in SD format. On top of that, most people don’t know that even the HD channels from DSTV are only broadcast in 1280pixels by 720 lines (i.e. not full HD).

So what on earth to do…?

Cliff’s Take

If you don’t own a TV, you don’t have much choice. Buy a full HDTV and learn to accept the picture when you watch the SD channels. Blu-ray DVDs and DSTV HD channels will look fantastic. And, unless you’re buying the TV for a medium-to-large room, I’d get a smaller screen like a 32-inch. The smaller pixels lessen the problems with viewing SD channels.

If you have a good SDTV ( I have a terrific Panasonic Plasma SD TV), keep it a while longer. The longer you wait, the cheaper (and better) the HDTVs will become, and more and more channels will switch over to an HD format. When a larger number of channels are available in HD, or your TV breaks, you can finally go and get the HDTV.

I hope I haven’t dampened your excitement about getting that gleaming new HDTV. My comments are obviously subjective and you may well find that SD channels look just fine in the shop. If you do, go-for-it. For now, I’ve decided to wait a while longer…

November 1st, 2011|