Lightspace refers to a vectorspace of greyscale pictures, or a modulespace of color pictures, linearized in Photographic Quantifiable Units.

A collection of differently exposed pictures of the same subject matter can be used to extend the dynamic range of a picture, or for artistic visual effects.

There is a freesource program called VideoOrbits that implements the CEMENT (Computer Enhanced Multiple Exposure Technique) algorithm. The [ program can be downloaded from Sourceforge] as part of the Comparametric Equations toolkit.