Scatter

When refering to photons and light, scattering describes the phenomenon of a source absorbing, and then emanating light in all directions. For example, when light from our sun comes into contact with the clouds in our atmosphere, it scatters, meaning it is absorbed by the clouds and the re-emitted in all directions. On a clear day the light seems to come from a small point, but on cloudy days it seems to come from all directions.

A concentration of artifacts.

See scattering.