How can I generate the Intensity Mapping Function from two histograms?

I have got histograms of two images taken at different exposure. How can I generate the Intensity Mapping Function from these histograms?

Answer 1

[Image Analyst]

Try imhistmatch(), or for something more accurate, try the one in my File Exchange http://www.mathworks.com/matlabcentral/fileexchange/28972-custom-shaped-histogram

For color, the best one I've seen is by Mark Grundland: http://www.eyemaginary.com/Portfolio/ColorHistogramWarp.html

Also see this by Brett Shoelson at the Mathworks: http://www.mathworks.com/matlabcentral/fileexchange/27396-matchhistograms

[Image Analyst]

ABC's "Answer" moved here:

This is what I want. I need the code to generate the last graph in the image

[Image Analyst]

Just make a line and clip it.

inputGrayLevels = 0 : 255;
outputGrayLevels = slope * (inputGrayLevels - centerGL);
% Clip
outputGrayLevels = max(outputGrayLevels, 0);
outputGrayLevels = min(outputGrayLevels, 255);