What is High-Definition Television (HDTV)? Simply put, HDTV offers more resolution or detail than standard resolution television. Television images are made up of lots of small rectangular dots called pixels, which change colors to create the image. A standard definition television has 640 pixels across and 480 pixels down. A high-definition television, on the other hand, typically has 1366 pixels across and 768 pixels down. You'll notice that the pixels in the width more than doubled while the pixels in the height didn't quite double. This is due to another difference between high-definition and standard definition programming: the aspect ratio or shape of the screen. Standard resolution television programs have a 4:3 ratio of pixels across to pixels down. For every four pixels across there are three pixels down. High-definition television operates on a wider window to more closely imitate our peripheral field of vision. HDTV programs are formatted in a 16:9 ratio of width pixels to height pixels. For comparison, a 4:3 ratio would be the same as 12:9 (4x3=12, 3x3=9). So for every 9 pixels down, high-definition programs have 16 pixels across, whereas standard definition programs only have 12 pixels across. If you've ever come across a high-definition television that looked terrible because people's faces looked stretched out, it's because someone is stretching a 4:3 program to fit on a 16:9 television. Ok, so there's more pixels, so what? The increase in resolution gives the images far more depth and clarity on the screen. The Difference is in The Details 480 lines of resolution stretched to fit 1080 lines 1080 lines of resolution This is particularly true at larger image sizes because the differences are more noticeable. For example, high-definition and standard-defintion will look pretty similar on a 13" screen, where the pixels are already tiny. On a 50" screen, however, the pixels are much larger. This results in a soft, blurry image at standard resolutions but remains sharp, crisp, and clear in high-definition. If you recall, tube TVs used to max out at about 35 or 36 inches. These beautiful large images combined with increased progress in flat panel and projection technologies have led us to televisions that look stunning, take up very little space, and feel like you're in a theater. Relative Image Sizes (1/10th Scale) Standard Television - 480 lines HDTV - 720 lines HDTV - 1080 lines Any other differences? I'm glad you asked. A lot of high-definition programming is also being encoded with 5.1 channels of sound, allowing viewers to combine the lifelike images on the television with a surround sound environment, immersing and engaging us in a whole new way. The true high definition experience is attained only when you combine a high-definition display with a minimum of 5.1 channels of audio.