System, method, and computer program for adjusting image contrast using parameterized cumulative distribution functions

Abstract

A system and method are provided for optimizing histogram cumulative distribution function curves. In use, a first cumulative distribution function for a first histogram of a first pixel region of a first image is computed, and a first set of parameters for the first cumulative distribution function is extracted. A second cumulative distribution function for a second histogram of a second pixel region of the first image is computed, and a second set of parameters for the second cumulative distribution function is extracted. An interpolated cumulative distribution function comprising interpolated parameters calculated by interpolating between the first set of parameters and the second set of parameters is created. Additionally, a first equalized pixel in a second image based on a first input pixel in the first image and the interpolated cumulative distribution function is generated.

What is claimed is: 
     
         1 . A device, comprising:
 a non-transitory memory storing instructions; and   one or more processors in communication with the non-transitory memory, wherein the one or more processors execute the instructions to:
 compute a first histogram based on a pixel region of a first image; 
 compute a first cumulative distribution function based on the first histogram; and 
 equalize a pixel at a first location of the pixel region, wherein the first location is based on at least one of:
 a preselected location, or 
 an object of interest. 
 
   
     
     
         2 . The device of  claim 1 , wherein the first cumulative distribution function includes a first set of parameters. 
     
     
         3 . The device of  claim 2 , wherein the first set of parameters further comprise an angle for each control point of the control points. 
     
     
         4 . The device of  claim 2 , further comprising create an interpolated cumulative distribution function comprising interpolated parameters calculated by interpolating between the first set of parameters and a second set of parameters. 
     
     
         5 . The device of  claim 4 , wherein the interpolated cumulative distribution function comprises a Bezier curve comprising interpolated control points and interpolated angles. 
     
     
         6 . The device of  claim 4 , wherein the interpolated cumulative distribution function comprises a spline curve comprising interpolated control points. 
     
     
         7 . The device of  claim 4 , wherein the interpolated parameters for the interpolated cumulative distribution function are weighted according to a position of the pixel at the first location of the pixel region. 
     
     
         8 . The device of  claim 7 , wherein the weighted interpolated parameters are applied horizontally. 
     
     
         9 . The device of  claim 7 , wherein the weighted interpolated parameters are applied vertically. 
     
     
         10 . The device of  claim 1 , wherein during a first processing pass on the first image, the one or more processors execute the instructions to generate and store parameters, including a first set of parameters and a second set of parameters, for at least the first pixel region of the first image and a second pixel region of the first image. 
     
     
         11 . The device of  claim 10 , wherein the first set of parameters and the second set of parameters are stored in a texture map. 
     
     
         12 . The device of  claim 4 , wherein the interpolating comprises bicubic interpolation. 
     
     
         13 . The device of  claim 1 , wherein the device is operable such that a first portion of pixel regions of the first image is selected based on a pixel of interest. 
     
     
         14 . The device of  claim 13 , wherein the device is operable such that the pixel of interest is associated with an identified object. 
     
     
         15 . The device of  claim 14 , wherein the device is operable such that a priority associated with the identified object is predetermined. 
     
     
         16 . A method, comprising:
 computing, using a processor, a first histogram based on a pixel region of a first image;   computing, using the processor, a first cumulative distribution function based on the first histogram; and   equalizing, using the processor, a pixel at a first location of the pixel region, wherein the first location is based on at least one of:
 a preselected location, or 
 an object of interest. 
   
     
     
         17 . A computer program product comprising computer executable instructions stored on a non-transitory computer readable medium that when executed by a processor instruct the processor to:
 compute a first histogram based on a pixel region of a first image;   compute a first cumulative distribution function based on the first histogram; and   equalize a pixel at a first location of the pixel region, wherein the first location is based on at least one of:
 a preselected location, or 
 an object of interest.