Atmospheric corrections
There are two approaches to atmospheric correction, these are:
Relative atmospheric correction: For relative atmospheric correction it is assumed that the haze component present in an image is additive. Dark pixel subtraction is a relative atmospheric correction approach.
Absolute atmospheric correction: "Absolute" correction uses atmospheric conditions and illumination and viewing geometries at the time of image acquisition to estimate the amount of scattering and absorption in each image band, and derives correction factors to re-scale the data from at-sensor to at-surface values.
References:
Jensen, JR (2005). Introductory digital image processing: a remote sensing perspective. Third edition, Prentice Hall: 316p.