Progressive Scan Rendering (Monitor / TV)

Progressive Scan

With the advent of home and office desktop computers, it was discovered that using a traditional television for the display of computer images did not yield good results, especially with text. This was due to the effect of interlaced scan. In order to produce a more pleasing and precise way of displaying images on a computer, progressive scan was developed.

Progressive scan differs from interlaced scan in that the image is displayed on a screen by scanning each line (or row of pixels) in a sequential order rather than an alternate order, as is done with interlaced scan. In other words, in progressive scan, the image lines (or pixel rows) are scanned in numerical order (1,2,3) down the screen from top to bottom, instead of in an alternate order (lines or rows 1,3,5, etc... followed by lines or rows 2,4,6). By progressively scanning the image onto a screen every 60th of a second rather than "interlacing" alternate lines every 30th of a second, a smoother, more detailed, image can be produced on the screen that is perfectly suited for viewing fine details, such as text, and is also less susceptible to interlace flicker.

Seeing this technology as way to improve the way we view images on a television screen, progressive scan has now been applied to the display of DVD and certain types of HDTV images.