occurs when you drive the phosphors harder than they should be driven. Phosphors can only take so much energy from the electron beam. The amount of energy they can take is partially limited by their ability to dissipate heat. In a black and white set, where the phosphors are continuous, heat dissipation is better than in a color set where phosphors are tiny, isolated areas; stripes in the case of most consumers TV sets, small dots in the case of many high resolution computer monitors. In CRT based projectors, phosphors are liquid cooled to increase their light output capability. When phosphors are driven harder than they should be, they disperse much of the extra energy to adjacent areas. It's sort of like sharing the load. The problem with sharing the load is that areas of the picture that shouldn't be lit up are lit up. That reduces the sets ability to show fine detail, not to mention slight light output changes near peak white. Blooming causes a softening of edges, a lack of gray scale detail near white, and often a change in color quality. Keeping a set out of blooming is therefore important to a good picture. Doing that requires turning the Contrast control way down. Since most sets come from the factory with the Contrast control turned all the way up, it will often be difficult for you to judge the real capability of a TV set when viewed in the store. An important consideration in purchasing a set is, will it produce a usable amount of light once the Contrast is turned down below the point of blooming. VE T11. Liquid cooling the phosphors introduces its own set of problems. In the case of CRT based projectors, the phosphors can be driven hard enough to decay in their light output capability. Light output capability from a device being driven this hard will often drop by as much as 50% in the first 1,000 to 2,000 hours of use. It will usually not drop much below the 50% point once it gets there as long as you don't drive the set into blooming. If you do overdrive the set, count on it burning the phosphors. I've encountered a number of circumstances where the tubes have to be replaced in as little as 800 hours, as opposed to the 10,000 hours that they should have lasted. It's possible to burn an ordinary TV set. Video games in particular have fixed patterns that will burn a set. Cable channels with fixed logos are also a potential source of burns. The most common is CNN. It is not unusual for me to see CNN Live burned into someone's set, all because they didn't turn the Contrast control down below the point of blooming. When you purchase a TV set, try not to take something off the showroom floor. The high contrast levels displayed at the store can shorten the useful life of the set. When you get your new set home, turn down the Contrast control first thing, then go through Video Essentials to set it up properly. VE T9-11.