DC RESTORATION

Ability of a set to hold black at black independent of picture content. In most sets the level of black floats, it goes up as the picture gets dim in content and goes back down as picture content gets brighter. The idea behind most sets having poor DC restoration is that consumers watch TV in high ambient light conditions. If the scene gets dark, the set pushes up the black so that you won't miss any detail. The problem with bringing black up is that it washes out the contrast of the picture. If you watch a set in well controlled ambient light, the change in black level and subsequent destruction of contrast ratio well make for poor viewing. The idea of DC Restoration is to clamp the back porch of the video signal to 0 Volts DC. (Synchronization signals go below that level and picture information goes above that level. The DC refers to Direct Current as AC refers to Alternating Current.) If you are looking for a high quality TV set, DC restoration should be at least 96%. It is actually difficult to get much above 98%. Even broadcast grade monitors are not perfect.