A video display using a large reflective screen and a separate projector mounted in front of the screen to project images onto the screen (as in a movie theater). Front projection video display systems are the ultimate performers in the world of audio/video. They offer the most options and the largest screen sizes along with potentially the best picture quality. here are a variety of projectors including LCD models (liquid crystal display), DLP models (digital light processing), light valve models and CRT models (cathode ray tubes). Of these the light valve and CRT projectors currently produce the best output while the LCD projectors are the least expensive. CRT projectors with a sufficient scan rate (known as data grade projectors) are able to produce line doubled and even line quadrupled images (needing a graphics grade projector) which vastly improve the picture quality of present day NTSC analog television. Data and graphics grade projectors are also able to take advantage of and project full HDTV images. These traits make front projection systems based on CRT projectors (those of sufficient quality and features) the most versatile and best performing display devices available today with the exception of light valve units. ight valve projectors feature higher light output than any other projector type along with the best quality, even surpassing that of graphics grade CRT projectors. However, light valve systems are prohibitively expensive for most home uses (typically costing a minimum of $50,000 with special set-up costs additional). This type of system is used primarily in commercial applications such as concerts and large auditoriums. CD and DLP projectors are the easiest to set up of the various types of projectors. LCD systems are the lowest cost, but they are also the poorest performers. LCD projectors are typically deficient in their ability to output true blacks and they do not output vast amounts of light. Additionally, the individual pixels tend to be visible with thin black lines between them. DLP projectors offer better color accuracy and excellent light output (especially from three chip designs which may approach the light output of a light valve projector). They also feature tightly packed pixels that improve on the LCD problem of individual pixels being separated by thin black lines. There are excellent LCD and DLP projectors, with LCD units offering the lowest cost while DLP units offer the higher quality level. ront projection systems work by shining light onto a reflective white screen. The light is reflected off the screen and back at the viewer who is able to see the images. Front projection systems must be properly set up in order to work optimally (as must all audio/video components, however, an improper set up is particularly detrimental to the large screen front projection system). The room must be dark for the screen and projector to work properly. Ambient light coming from windows or lamps tends to interfere with the light travelling from the projector and bouncing back off the screen washing it out much like how the a photograph can be washed out with too much light. Additionally, the viewers must be seated far enough back so that the scan lines are not discernable individually (this is true of all video displays but especially for front projection systems with their large screens which can easily show scan lines and image errors).