Redundancy is the amount of space wasted in the storage media recording pictorial information digitally. Redundancy occurs in two ways: temporal redundancy and spatial redundancy. When a video image is taken, the image is shot in frames per second. In this series of images, a pixel can remain in a fixed location for a period of time. This is temporal redundancy.
Spatial redundancy occurs within one frame. Pixels can be spread or compressed in an image so the space the image consumes in storage can be large if the pixels are spread out. Shrinking the pixels reduces the file size.