In contrast to the entirely digital DVD, LaserDiscs use only analog video. As the LaserDisc format is not digitally encoded and does not make use of compression techniques, it is immune to video macroblocking (most visible as blockiness during high motion sequences) or contrast banding (subtle visible lines in gradient areas, such as out-of-focus backgrounds, skies, or light casts from spotlights) that can be caused by the MPEG-2 encoding process as video is prepared for DVD. Early DVD releases held the potential to surpass their LaserDisc counterparts, but often managed only to match them for image quality, and in some cases, the LaserDisc version was preferred. However, proprietary human-assisted encoders manually operated by specialists can vastly reduce the incidence of artifacts, depending on playing time and image complexity. By the end of LaserDisc's run, DVDs were living up to their potential as a superior format.