Articles

Dot Crawl

All televisions are subject to a problem called "dot crawl". This shows up along horizontal or diagonal edges of objects that have primer-image-place-holder.jpgcontrasting colors (for example, yellow adjacent to blue), and looks like a moving stairway (escalator). It is caused by the imperfect ability of the comb filter in the TV (or video player) to separate the color signal from the luminance (brightness) because the frequencies overlap. The amount of dot crawl varies with the quality of the TV, but also those units with special image processing features that allow you to enlarge the picture to fill the screen (in "widescreen" TVs; see below) or to magnify a part of the image you want to see in more detail, may be particularly prone to exaggerated dot crawl. Therefore, look for this artifact when choosing a television, especially those with sophisticated arrays of image manipulating capabilities.