图像处理---CLAHE（限制对比度自适应直方图均衡）算法MATLAB代码

function out = myCLAHE(I)

%ADAPTHISTEQ Contrast-limited Adaptive Histogram Equalization (CLAHE).
%   ADAPTHISTEQ enhances the contrast of images by transforming the
%   values in the intensity image I.  Unlike HISTEQ, it operates on small
%   data regions (tiles), rather than the entire image. Each tile's 
%   contrast is enhanced, so that the histogram of the output region
%   approximately matches the specified histogram. The neighboring tiles 
%   are then combined using bilinear interpolation in order to eliminate
%   artificially induced boundaries.  The contrast, especially
%   in homogeneous areas, can be limited in order to avoid amplifying the
%   noise which might be present in the image.

%--------------------------- The algorithm ----------------------------------
%
%  1. Obtain all the inputs: 
%    * image
%    * number of regions in row and column directions
%    * number of bins for the histograms used in building image transform
%      function (dynamic range)
%    * clip limit for contrast limiting (normalized from 0 to 1)
%    * other miscellaneous options
%  2. Pre-process the inputs:  
%    * determine real clip limit from the normalized value
%    * if necessary, pad the image before splitting it into regions
%  3. Process each contextual region (tile) thus producing gray level mappings
%    * extract a single image region
%    * make a histogram for this region using the specified number of bins
%    * clip the histogram using clip limit
%    * create a mapping (transformation function) for this region
%  4. Interpolate gray level mappings in order to assemble final CLAHE image
%    * extract cluster of four neighboring mapping functions
%    * process image region partly overlapping each of the mapping tiles
%    * extract a single pixel, apply four mappings to that pixel, and 
%      interpolate between the results to obtain the output pixel; repeat
%      over the entire image
%
%  See code for further details.
%
%-----------------------------------------------------------------------------

dimI = size(I);% 图像大小

% 'NumTiles'  Two-element vector