In graphics and video editing dissolve is a term used to describe a transition effect in which one video clip (or one image) is gradually fads out while another image simultaneously replaces the original one. Also called video dissolve, film dissolve, or linear light blend. The overall objective is for the image or clip to appear to seamlessly transition from one image to the other in a fluid motion.
Linear light blend (a.k.a. film dissolve) If you've used Avid editing systems, you're probably familiar with the .film dissolve. transition effect that is offered alongside regular video dissolve. Film dissolve is supposed to morely closely approximate the look of a traditional optical dissolve effect created by printing film frames on top of each other at varying exposures.