HDTV Resolution Guide

The term "1080p" means 1080 horizontal lines, progressive. If that does not make much sense, it will at the end of this article.
1080p Explained

Pixels

Televisions create an image with thousands of square dots (pixels) lined up, much like graph paper. 1080 means there are 1,080 rows of lines from the top of the screen to the bottom of the screen. The more lines there are, the smaller each individual pixel becomes, making the final image sharper. To keep each dot square requires the grid to contain vertical lines as well. On a 1080p TV, there are 1920 horizontal lines and 1080 vertical lines for a grand total of just over 2 million total pixels. The latest Ultra HD 4K TVs have a resolution of 3840 x 2160 pixels for a grand total of over 8 million pixels! This is the highest possible resolution currently availabe on the consumer market.

This is a lot of information, but the take home message is this. More lines mean a clearer picture. It is important to remember that a television can display fewer lines, but not more lines. So, a 1080p television can display 720p without problems, but a 720p television cannot display 1080p.

Progressive vs. Interlaced

TVs "draw" or refresh the picture on the screen one line at a time. With 1080 lines to draw, this process happens very rapidly. When watching TV, viewers may notice that some programs will show 1080i while others may display 1080p. The "i" and "p" stand for interlaced and progressive. Interlaced broadcasts will refresh half the lines on the screen at a time (odd, then even) whereas progressive broadcasts refresh all lines on the screen simultaneously. Interlaced video can sometimes experience flickering while progressive video will be smooth and clear. Progressive broadcasts take more bandwidth and are consequently not common with satellite or cable programs. Most DVD & Blu-ray discs will display progressive as bandwidth is no problem. More information on this, and other HDTV topics, can be found in the Learning Center.

Aspect Ratio

Newer HDTVs also have a 16:9 aspect ratio compared to older square screen TVs with a 4:3 aspect ratio. Most HDTV broadcasts are recorded in 16:9 as are many movies. On occasion, movies are filmed in a wider aspect ratio resulting in black bars on the top and bottom of the screen. This is normal and should not cause concern among viewers. In addition, if an older non-HD TV program is viewed on a new 16:9 TV, black bars will appear on the left and right sides of the screen. Older television programs were filmed in the 4:3 ratio and do not fit well on a wide screen TV.