System for expanding the video contrast of an image

Abstract

A system, and method, is disclosed for substantially increasing the dynamic range of contrast of an input sequence of pixels representative of an image. In a preferred embodiment a first circuit is responsive to an input sequence of pixels representative of an image for developing bias and gain parameters. These bias and gain parameters are respectively utilized by first and second function generators to generate bias correction signals and gain correction signals, respectively. A delay circuit delays the input sequence of pixels to synchronize said input sequence with the bias correction signals and the gain correction signals. A first expansion circuit expands in a first direction the range of contrast of the delayed input sequence of pixels as a function of the bias correction signals to produce a first contrast expanded sequence of pixels. A second expansion circuit expands in a second direction the range of contrast of the first contrast expanded sequence of pixels as a function of the gain correction signals to produce an output sequence of pixels which has a substantially expanded dynamic range of contrast in relation to the dynamic range of contrast of the input sequence of pixels.