How HDTV Produces a Better Picture

High definition television was designed with a better picture in mind. A high-resolution picture starts with the way the picture is transmitted. Traditional television programming is broadcast on an analog radio frequency signal. With analog broadcasts, the height (amplitude) of the radio wave represents various aspects of the signal, such as color and brightness. HDTV programming replaces the analog signal with a digital one. Digital signals carry the same information that was in the analog signal, but the information is encoded as a series of binary digital bits -- groupings of 0s and 1s.

The primary advantage of digital transmission is that all those binary bits recombine to reproduce an exact copy of the original source signal. Because digital signals are comprised of binary bits, a 1 is always a 1 and a 0 is always a 0. This fidelity to the original source is why digital TV transmission results picture and sound quality, no matter what the source.

That said, digital transmission isn't limited to high definition television; you can also transmit standard definition signals digitally. What makes a picture high definition is the resolution of the picture, and that starts on the very smallest level, in the form of a screen element known as a pixel.

Each pixel is comprised of three closely spaced "dots" of color -- red, green, and blue -- arranged in rows and columns. The pixels are so close together that, from the proper distance, they appear connected, and create a complete picture.

The easiest way to increase picture resolution is to stuff more of these pixels onto the screen, by using smaller pixels. This is what HDTV does. For example, in the 1080i HDTV format, eighteen pixels can fit in the same space occupied by four pixels used in traditional television sets.

And it's not just size, it's also shape. HDTV pixels are smaller than SDTV pixels, yes, but they're also squarer. This enables an HDTV display to resolve finer details and hold smoother curves. The square pixels also remove some of the image distortion seen on older televisions.

By using these smaller, squarer pixels, an HDTV picture can contain up to seven times the total number of pixels found in a standard definition picture. The 1080i format uses more than 2 million individual pixels, compared with just 300,000 pixels in a traditional television screen. And that's why HDTV looks so much better than regular standard definition television.

Michael Miller is a writer and commentator on technology and digital lifestyle topics.