Projector brightness: "light out" is the projector main technical indicators, "light out" usually represented by luminous flux, luminous flux is to describe the strength of light radiation generated visual response per unit of time, the unit is lumen.
Projector indicate units of luminous flux standards ANSI lumens, ANSI lumens is a United States National Association for Standardization method for measuring luminous flux of the projector, and determination are as follows: 1) the distance between the projector and the screen: 2.4 m.
2) 60 inches.
3) with photometric measurement screen "field" font nine at the intersection point of illumination, multiplied by the area by 9 projection screen brightness.
4) finds the average of 9 points luminance, that is ANSI lumens.

Comparison of brightness: LCD projectors are transparencies for projection mode, rely mainly on improving light efficiency, reduced energy consumption, improved LCD panel open the optical component rate and the installation of micro lenses and other technical means to increase the brightness. DLP projection technology is reflection, mainly by improving the color filler of technology, changing means of mirror inclination angle and reducing optical loss increase brightness target. As the projector product development, each manufacturer has introduced with high brightness projectors, projector brightness most of 2000ANSI lumens or more. 
    Various brands of projectors due to differences in determination, while ANSI lumens the same, but the actual brightness is different. Projector brightness test, and users, and from the distance of the screen and the projector screen angle, as well as screen gain indicators have a lot to do. Products of different brightness differences mainly in the crisp image clarity, color, light and dark gray levels, that is, clearer images with high brightness, high color more crisp, light and dark gray to show a more complete. For ordinary text, difference in brightness on an image effect is not obvious. 
Comparison of different manufacturers for brightness settings also, most products are clear and complete within the brightness can be adjusted to display images, and some of the products after the brightness to more than 90%, the screen went blank, such practical applications of high brightness for the user is clearly of no practical significance.    

Projector brightness and screen options: brightness projectors light intensity of the output to the screen and the brightness of the projected image. Typically, the higher the brightness of the projector, projecting to the same dimensions as the image on the screen is brighter, the images clearer. However the human eyes can sense the brightness of an image does not just depend on the brightness of the projector, and the ambient light intensity, the dimensions of the image has a lot to do. Stronger the ambient light, human eyes perceive the brightness of the image relative to the more sombre. Therefore users will on the basis of their own environmental conditions to select the brightness of the projector, is not necessarily the brighter the better. Because, in other indicator under the same conditions, higher brightness, projector prices will be higher, while the human eye perceived brightness of the image will have a certain scope exceeds this range, people will feel uncomfortable, especially watching the image brightness is too high for a long time can make you look tired, and caused some damage. Users need to be reminded of is, in addition to select the brightness indicators according to the size, also taking into account environmental factors such as lighting conditions and screen type. The same brightness, different ambient light conditions, and different screen types will have a different look. When users select projectors, for brightness target to have more than one degree. As the brightness of the projector very much depends on the projector bulb lamp light output will decay as the time inevitably causes reduced brightness of the projector.
Products after 2000 hours of use of the projector brightness decay quickly, so users in the choice of projector products, be sure to brightness target has a comprehensive consideration.
     In General, at 40-50 square meters at home or living room, the projector between the recommended brightness 800-1200 lumens, screen select 60 inches to 72 inches; 60-100 square in a small conference room or standard classroom, recommends that the choice of 1500-2000 between the lumen projector brightness, screen select 80 inches to 100 inches; in 120-200 square meters of medium sized meeting rooms and a lecture theatre, between the recommended projector brightness 2000-3000 lumens, Select 120 inch curtain corresponds to 150 inches; in the large conference room or auditorium of 300 square meters, most projectors are professional engineering you want to select more than 3,000 lumens, curtains are more than 200 inches.