Aspect Ratios

• The size of a TV set usually tells the diagonal measurement from adjacent corners across the face of the screen. The aspect ratio for standard television is 4-to-3, telling the relationship between the horizontal measurement and the vertical. For example, if it's 12 inches high, it will be 16 inches wide and 20 inches from corner to corner. High-definition TV has an aspect ratio of 16-to-9. TV screen measurements are approximate but exact dimensions are usually stated in the specifications in the owner's manual.
  
  

Video Signals

• Whether a TV signal is in standard or high definition depends on how the broadcaster produces it. A standard TV with an aspect ratio of four to three fills the screen with a standard signal but shows HD signals with black edges above and below, giving the picture an aspect ratio of 16-to-9. An HDTV has adjustments to stretch or magnify standard TV signals to fit the screen or show them in either a standard or HD aspect ratio, sometimes with black edges. When an HDTV receives an HD signal, it fills the screen more accurately.
  
  

Resolution

• Resolution tells the amount information sent or the amount of pixels or dots a TV can illuminate. The specification uses a number to tell horizontal lines that can be produced with a letter telling the type of scanning. Standard TVs produce 480i resolution with interlaced scanning that illuminates odd lines in one sweep and even in the next. HDTVs have 780p, 1080i or 1080p resolution with progressive scanning that illuminates all lines in one sweep. The broadcaster determines the resolution of signals sent and the design of the TV tells how it presents them to the screen.
  
  

Formats

• Television sets and cable and satellite receivers have various connection formats. A composite video connection uses a single coaxial connection for video and carries only standard signals. Component video uses three coaxial connections for video and carries standard or HD signals. An HDMI connection uses a single 19-pin cable that carries digital HD and includes sound. The aspect ratio that appears on your screen depends on the type of signal sent by the broadcaster and your TV set design and settings. The cable or satellite connection provider makes no difference.