What is High Definition TV?

High definition TV produces the highest standard of picture quality. Standard T.V. pictures are transmitted with a picture resolution of 625 horizontal scanning lines which are refreshed 50 times every second (50 Hz).

DVD pictures are a higher resolution of 720 vertical lines by 576 horizontal lines. This produces the good quality crisp detailed picture we associate with DVD.

High definition produces a resolution of 1280 vertical lines by 720 horizontal lines. This is almost double the quality of DVD and produces twice as much detail resulting in a sharper, cleaner image with much better colour separation and depth of field.

A second standard of high definition utilises a ultra high resolution of 1920 x 1080 lines which is commonly shown as an interlaced picture because of the massive amount of detail needing to be redrawn every frame.

But the very latest video scalars and projectors are capable of displaying a 1920 x 1080 progressively scanned picture which means that you get the absolute best of both worlds with the incredible detail level combined with the smooth motion and picture crispness of a progressively scanned image.

Interlacing means that only half the image is shown at once, with the other half shown a split second latter, i.e. odd lines shown first then even lines shown after.

Interlacing was used historically due to the poor quality of old displays which could not draw all the lines off an image quickly enough so reverted to interlacing the picture. However, now plasma, LCD and DLP technologies are capable of drawing images at sufficient speeds to show the entire picture frame on the screen at once, termed progressive scan Progressively scanned images produce a more detailed smoother moving image with finer detail.

To summarise the very best picture quality available is a progressively scanned 1920 x 1080 image, which can currently only be displayed on the very best displays. The quality is simply staggering and makes normal DVD seem like an old video tape by comparison. To be truly future proofed and able to play any movie or TV station produced in the future, a 1080 progressive display is the only option.