VIDEO CONTRAST ENHANCEMENT WITH SUB-SEGMENTS

摘要

A system and method for image contrast enhancement using sub-segments. A coarse piecewise linear transform is formed based on the intensity distribution in an image, the segments of the piecewise linear transform selected to produce, when the piecewise linear transform is applied to the image, an improved intensity distribution, e.g., one approximating a Rayleigh distribution. A fine piecewise linear transform is formed by forming sub-segments at each of the breakpoints of the coarse piecewise linear transform.

主权项

1. A method for processing an input image comprising intensity values, the method comprising:
calculating an intensity value distribution for the input image; forming a first piecewise linear transform,
the first piecewise linear transform configured to transform the intensity distribution of the input image,the first piecewise linear transform comprising a sequence of first segments,each segment of the sequence of first segments having a gain,
the sequence of first segments being connected at a first plurality of breakpoints,the difference between the respective gains of any pair of segments, of the sequence of first segments, connected at a breakpoint of the first plurality of breakpoints being less than a first gain change limit, forming a second piecewise linear transform,
the second piecewise linear transform comprising a sequence of second segments corresponding to a pair of first segments connected at one of the first plurality of breakpoints,each segment of the sequence of second segments having a gain,the sequence of second segments being connected at a second plurality of breakpoints,the difference between the respective gains of any pair of segments, of the sequence of second segments, connected at a breakpoint of the second plurality of breakpoints being less than a second gain change limit,the second gain change limit being less than the first gain change limit; and mapping the intensity values of the input image to modified intensity values using the second linear piecewise transform.