What does 1080p mean to me?

720p/60 or 1080i/60 or 1080p/30 or 1080p/60?

This is the Da Vinci Code of High Definition Television.

If you can decipher these numbers you’ll know almost everything you’ll need to know about High Definition video.

There are just three things you need to know to decipher the High Definition code. Resolution, Scan Type and the Frame Rate.

HD comes in 2 resolutions 1080 and 720. The number stands for the vertical resolution of the picture. A 1080 image has 1.5 times the vertical resolution of a 720 image. (It also has 1.5 times the horizontal resolution giving the 1080 image twice the number of pixels as the 720).

The Scan Type is the method the picture was captured. There are two choices here – Progressive and Interlace. In Progressive the picture is drawn on the screen one line at a time starting from the top. When the picture is complete, it's erased and the next picture is drawn on. This happens so fast that it appears to our eye to be one continuous moving image. Interlace scanning first draws every odd numbered line on the screen – one at a time from the top, erases them and then draws every even line on the screen. I know this seems crazy but it's a holdover from the early days of television where it was a way to reduce flicker and improve detail. It's used today because of its compatibility with tube TV sets.

Frame Rate is the number of pictures per second that the video delivers. You typically see only three common frame rates – 24, 30 and 60. (There are three more – 23.976, 29.97 and 59.94 that are used to be compatible with the tube televisions but you rarely see them mentioned). The only weird thing to remember here is when you're referring to an interlace scanned image (where half the picture is drawn at a time) the frame rate number refers to the number of half pictures per second (60 half pictures works out to 30 whole pictures per second – why they just don’t use 30 probably has to do with some engineering mumbo-jumbo).

That’s everything you need to know to decode that mysterious HD code. So when you see 1080p/30 you will know that the picture resolution is 1080 lines, progressive scan type and at 30 frames per second or 1080i/60 is a 1080 resolution image and 60 half pictures per second.

Wow.

~George