retinex算法的三种源码

转自：http://blog.csdn.net/carson2005/article/details/9455641

源码，retinex算法的三种，其源码是国外一个研究生的毕设项目

头文件：

 /*
  * Copyright (c) 2006, Douglas Gray ([email protected], [email protected])
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *     * Redistributions of source code must retain the above copyright
  *       notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above copyright
  *       notice, this list of conditions and the following disclaimer in the
  *       documentation and/or other materials provided with the distribution.
  *     * Neither the name of the  nor the
  *       names of its contributors may be used to endorse or promote products
  *       derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY Douglas Gray ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL  BE LIABLE FOR ANY
  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #pragma once

 #include "cv.h"

 extern double* CreateKernel(double sigma);
 extern int* CreateFastKernel(double sigma);

 extern void FilterGaussian(IplImage* img, double sigma);
 extern void FastFilter(IplImage *img, double sigma);

 extern void Retinex
 (IplImage *img, double sigma, int gain = 128, int offset = 128);

 extern void MultiScaleRetinex
 (IplImage *img, int scales, double *weights, double *sigmas, int gain = 128, int offset = 128);

 extern void MultiScaleRetinexCR
 (IplImage *img, int scales, double *weights, double *sigmas, int gain = 128, int offset = 128,
  double restoration_factor = 6, double color_gain = 2);

实现：

 /*
  * Copyright (c) 2006, Douglas Gray ([email protected], [email protected])
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are met:
  *     * Redistributions of source code must retain the above copyright
  *       notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above copyright
  *       notice, this list of conditions and the following disclaimer in the
  *       documentation and/or other materials provided with the distribution.
  *     * Neither the name of the  nor the
  *       names of its contributors may be used to endorse or promote products
  *       derived from this software without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY Douglas Gray ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL  BE LIABLE FOR ANY
  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
  * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 #include "retinex.h"

 #include

 //#define USE_EXACT_SIGMA


 #define pc(image, x, y, c) image->imageData[(image->widthStep * y) + (image->nChannels * x) + c]

 #define INT_PREC 1024.0
 #define INT_PREC_BITS 10

 inline double int2double(int x) { return (double)x / INT_PREC; }
 inline int double2int(double x) { return (int)(x * INT_PREC + 0.5); }

 inline int int2smallint(int x) { return (x >> INT_PREC_BITS); }
 inline int int2bigint(int x) { return (x << INT_PREC_BITS); }

 //
 // CreateKernel
 //
 // Summary:
 // Creates a normalized 1 dimensional gaussian kernel.
 //
 // Arguments:
 // sigma - the standard deviation of the gaussian kernel.
 //
 // Returns:
 // double* - an array of values of length ((6*sigma)/2) * 2 + 1.
 //
 // Note:
 // Caller is responsable for deleting the kernel.
 //
 double*
 CreateKernel(double sigma)
 {
     int i, x, filter_size;
     double* filter;
     double sum;

     // Reject unreasonable demands
     if ( sigma > 200 ) sigma = 200;

     // get needed filter size (enforce oddness)
     filter_size = (int)floor(sigma*6) / 2;
     filter_size = filter_size * 2 + 1;

     // Allocate kernel space
     filter = new double[filter_size];

     // Calculate exponential
     sum = 0;
     for (i = 0; i < filter_size; i++) {
         x = i - (filter_size / 2);
         filter[i] = exp( -(x*x) / (2*sigma*sigma) );

         sum += filter[i];
     }

     // Normalize
     for (i = 0, x; i < filter_size; i++)
         filter[i] /= sum;

     return filter;
 }

 //
 // CreateFastKernel
 //
 // Summary:
 // Creates a faster gaussian kernal using integers that
 // approximate floating point (leftshifted by 8 bits)
 //
 // Arguments:
 // sigma - the standard deviation of the gaussian kernel.
 //
 // Returns:
 // int* - an array of values of length ((6*sigma)/2) * 2 + 1.
 //
 // Note:
 // Caller is responsable for deleting the kernel.
 //

 int*
 CreateFastKernel(double sigma)
 {
     double* fp_kernel;
     int* kernel;
     int i, filter_size;

     // Reject unreasonable demands
     if ( sigma > 200 ) sigma = 200;

     // get needed filter size (enforce oddness)
     filter_size = (int)floor(sigma*6) / 2;
     filter_size = filter_size * 2 + 1;

     // Allocate kernel space
     kernel = new int[filter_size];

     fp_kernel = CreateKernel(sigma);

     for (i = 0; i < filter_size; i++)
         kernel[i] = double2int(fp_kernel[i]);

     delete fp_kernel;

     return kernel;
 }


 //
 // FilterGaussian
 //
 // Summary:
 // Performs a gaussian convolution for a value of sigma that is equal
 // in both directions.
 //
 // Arguments:
 // img - the image to be filtered in place.
 // sigma - the standard deviation of the gaussian kernel to use.
 //
 void
 FilterGaussian(IplImage* img, double sigma)
 {
     int i, j, k, source, filter_size;
     int* kernel;
     IplImage* temp;
     int v1, v2, v3;

     // Reject unreasonable demands
     if ( sigma > 200 ) sigma = 200;

     // get needed filter size (enforce oddness)
     filter_size = (int)floor(sigma*6) / 2;
     filter_size = filter_size * 2 + 1;

     kernel = CreateFastKernel(sigma);

     temp = cvCreateImage(cvSize(img->width, img->height), img->depth, img->nChannels);

     // filter x axis
     for (j = 0; j < temp->height; j++)
     for (i = 0; i < temp->width; i++) {

         // inner loop has been unrolled

         v1 = v2 = v3 = 0;
         for (k = 0; k < filter_size; k++) {

             source = i + filter_size / 2 - k;

             if (source < 0) source *= -1;
             if (source > img->width - 1) source = 2*(img->width - 1) - source;

             v1 += kernel[k] * (unsigned char)pc(img, source, j, 0);
             if (img->nChannels == 1) continue;
             v2 += kernel[k] * (unsigned char)pc(img, source, j, 1);
             v3 += kernel[k] * (unsigned char)pc(img, source, j, 2);

         }

         // set value and move on
         pc(temp, i, j, 0) = (char)int2smallint(v1);
         if (img->nChannels == 1) continue;
         pc(temp, i, j, 1) = (char)int2smallint(v2);
         pc(temp, i, j, 2) = (char)int2smallint(v3);

     }

     // filter y axis
     for (j = 0; j < img->height; j++)
     for (i = 0; i < img->width; i++) {

         v1 = v2 = v3 = 0;
         for (k = 0; k < filter_size; k++) {

             source = j + filter_size / 2 - k;

             if (source < 0) source *= -1;
             if (source > temp->height - 1) source = 2*(temp->height - 1) - source;

             v1 += kernel[k] * (unsigned char)pc(temp, i, source, 0);
             if (img->nChannels == 1) continue;
             v2 += kernel[k] * (unsigned char)pc(temp, i, source, 1);
             v3 += kernel[k] * (unsigned char)pc(temp, i, source, 2);

         }

         // set value and move on
         pc(img, i, j, 0) = (char)int2smallint(v1);
         if (img->nChannels == 1) continue;
         pc(img, i, j, 1) = (char)int2smallint(v2);
         pc(img, i, j, 2) = (char)int2smallint(v3);

     }


     cvReleaseImage( &temp );

     delete kernel;

 }

 //
 // FastFilter
 //
 // Summary:
 // Performs gaussian convolution of any size sigma very fast by using
 // both image pyramids and seperable filters.  Recursion is used.
 //
 // Arguments:
 // img - an IplImage to be filtered in place.
 //
 void
 FastFilter(IplImage *img, double sigma)
 {
     int filter_size;

     // Reject unreasonable demands
     if ( sigma > 200 ) sigma = 200;

     // get needed filter size (enforce oddness)
     filter_size = (int)floor(sigma*6) / 2;
     filter_size = filter_size * 2 + 1;

     // If 3 sigma is less than a pixel, why bother (ie sigma < 2/3)
     if(filter_size < 3) return;

     // Filter, or downsample and recurse
     if (filter_size < 10) {

 #ifdef USE_EXACT_SIGMA
         FilterGaussian(img, sigma)
 #else
         cvSmooth( img, img, CV_GAUSSIAN, filter_size, filter_size );
 #endif

     }
     else {
         if (img->width < 2 || img->height < 2) return;

         IplImage* sub_img = cvCreateImage(cvSize(img->width / 2, img->height / 2), img->depth, img->nChannels);

         cvPyrDown( img, sub_img );

         FastFilter( sub_img, sigma / 2.0 );

         cvResize( sub_img, img, CV_INTER_LINEAR );

         cvReleaseImage( &sub_img );
     }

 }

 //
 // Retinex
 //
 // Summary:
 // Basic retinex restoration.  The image and a filtered image are converted
 // to the log domain and subtracted.
 //
 // Arguments:
 // img - an IplImage to be enhanced in place.
 // sigma - the standard deviation of the gaussian kernal used to filter.
 // gain - the factor by which to scale the image back into visable range.
 // offset - an offset similar to the gain.
 //
 void
 Retinex(IplImage *img, double sigma, int gain, int offset)
 {
     IplImage *A, *fA, *fB, *fC;

     // Initialize temp images
     fA = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, img->nChannels);
     fB = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, img->nChannels);
     fC = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, img->nChannels);

     // Compute log image
     cvConvert( img, fA );
     cvLog( fA, fB );

     // Compute log of blured image
     A = cvCloneImage( img );
     FastFilter( A, sigma );
     cvConvert( A, fA );
     cvLog( fA, fC );

     // Compute difference
     cvSub( fB, fC, fA );

     // Restore
     cvConvertScale( fA, img, gain, offset);

     // Release temp images
     cvReleaseImage( &A );
     cvReleaseImage( &fA );
     cvReleaseImage( &fB );
     cvReleaseImage( &fC );

 }

 //
 // MultiScaleRetinex
 //
 // Summary:
 // Multiscale retinex restoration.  The image and a set of filtered images are
 // converted to the log domain and subtracted from the original with some set
 // of weights. Typicaly called with three equaly weighted scales of fine,
 // medium and wide standard deviations.
 //
 // Arguments:
 // img - an IplImage to be enhanced in place.
 // sigma - the standard deviation of the gaussian kernal used to filter.
 // gain - the factor by which to scale the image back into visable range.
 // offset - an offset similar to the gain.
 //
 void
 MultiScaleRetinex(IplImage *img, int scales, double *weights, double *sigmas, int gain, int offset)
 {
     int i;
     double weight;
     IplImage *A, *fA, *fB, *fC;

     // Initialize temp images
     fA = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, img->nChannels);
     fB = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, img->nChannels);
     fC = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, img->nChannels);


     // Compute log image
     cvConvert( img, fA );
     cvLog( fA, fB );

     // Normalize according to given weights
     for (i = 0, weight = 0; i < scales; i++)
         weight += weights[i];

     if (weight != 1.0) cvScale( fB, fB, weight );

     // Filter at each scale
     for (i = 0; i < scales; i++) {
         A = cvCloneImage( img );
         FastFilter( A, sigmas[i] );

         cvConvert( A, fA );
         cvLog( fA, fC );
         cvReleaseImage( &A );

         // Compute weighted difference
         cvScale( fC, fC, weights[i] );
         cvSub( fB, fC, fB );
     }

     // Restore
     cvConvertScale( fB, img, gain, offset);

     // Release temp images
     cvReleaseImage( &fA );
     cvReleaseImage( &fB );
     cvReleaseImage( &fC );
 }

 //
 // MultiScaleRetinexCR
 //
 // Summary:
 // Multiscale retinex restoration with color restoration.  The image and a set of
 // filtered images are converted to the log domain and subtracted from the
 // original with some set of weights. Typicaly called with three equaly weighted
 // scales of fine, medium and wide standard deviations. A color restoration weight
 // is then applied to each color channel.
 //
 // Arguments:
 // img - an IplImage to be enhanced in place.
 // sigma - the standard deviation of the gaussian kernal used to filter.
 // gain - the factor by which to scale the image back into visable range.
 // offset - an offset similar to the gain.
 // restoration_factor - controls the non-linearaty of the color restoration.
 // color_gain - controls the color restoration gain.
 //
 void
 MultiScaleRetinexCR(IplImage *img, int scales, double *weights, double *sigmas,
                     int gain, int offset, double restoration_factor, double color_gain)
 {
     int i;
     double weight;
     IplImage *A, *B, *C, *fA, *fB, *fC, *fsA, *fsB, *fsC, *fsD, *fsE, *fsF;

     // Initialize temp images
     fA = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, img->nChannels);
     fB = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, img->nChannels);
     fC = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, img->nChannels);
     fsA = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, 1);
     fsB = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, 1);
     fsC = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, 1);
     fsD = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, 1);
     fsE = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, 1);
     fsF = cvCreateImage(cvSize(img->width, img->height), IPL_DEPTH_32F, 1);

     // Compute log image
     cvConvert( img, fB );
     cvLog( fB, fA );

     // Normalize according to given weights
     for (i = 0, weight = 0; i < scales; i++)
         weight += weights[i];

     if (weight != 1.0) cvScale( fA, fA, weight );

     // Filter at each scale
     for (i = 0; i < scales; i++) {
         A = cvCloneImage( img );
         FastFilter( A, sigmas[i] );

         cvConvert( A, fB );
         cvLog( fB, fC );
         cvReleaseImage( &A );

         // Compute weighted difference
         cvScale( fC, fC, weights[i] );
         cvSub( fA, fC, fA );
     }

     // Color restoration
     if (img->nChannels > 1) {
         A = cvCreateImage(cvSize(img->width, img->height), img->depth, 1);
         B = cvCreateImage(cvSize(img->width, img->height), img->depth, 1);
         C = cvCreateImage(cvSize(img->width, img->height), img->depth, 1);

         // Divide image into channels, convert and store sum
         cvCvtPixToPlane( img, A, B, C, NULL );

         cvConvert( A, fsA );
         cvConvert( B, fsB );
         cvConvert( C, fsC );

         cvReleaseImage( &A );
         cvReleaseImage( &B );
         cvReleaseImage( &C );

         // Sum components
         cvAdd( fsA, fsB, fsD );
         cvAdd( fsD, fsC, fsD );

         // Normalize weights
         cvDiv( fsA, fsD, fsA, restoration_factor);
         cvDiv( fsB, fsD, fsB, restoration_factor);
         cvDiv( fsC, fsD, fsC, restoration_factor);

         cvConvertScale( fsA, fsA, 1, 1 );
         cvConvertScale( fsB, fsB, 1, 1 );
         cvConvertScale( fsC, fsC, 1, 1 );

         // Log weights
         cvLog( fsA, fsA );
         cvLog( fsB, fsB );
         cvLog( fsC, fsC );

         // Divide retinex image, weight accordingly and recombine
         cvCvtPixToPlane( fA, fsD, fsE, fsF, NULL );

         cvMul( fsD, fsA, fsD, color_gain);
         cvMul( fsE, fsB, fsE, color_gain );
         cvMul( fsF, fsC, fsF, color_gain );

         cvCvtPlaneToPix( fsD, fsE, fsF, NULL, fA );
     }

     // Restore
     cvConvertScale( fA, img, gain, offset);

     // Release temp images
     cvReleaseImage( &fA );
     cvReleaseImage( &fB );
     cvReleaseImage( &fC );
     cvReleaseImage( &fsA );
     cvReleaseImage( &fsB );
     cvReleaseImage( &fsC );
     cvReleaseImage( &fsD );
     cvReleaseImage( &fsE );
     cvReleaseImage( &fsF );
 }

 

 

这种混合算法代码：

我参考一个matlab代码写的 

c版

 // author : [email protected]
 // data   : 4/20/2011
 /*
 %%%%%%%%%%%%%%%RGB normalization%%%%%%%%%%%%%%%%%%%%%%
 %its cascaded implementation of 1 section of paper "A FAST SKIN REGION DETECTOR" by
 %Phil Chen, Dr.Christos Greecos
 %and
 %section 2.1 of paper "Simple and accurate face detection in color images" by
 %YUI TING PAI et al
 % Coding by Madhava.S.Bhat, Dept of Electronics an communication
 %Dr.Ambedkar Institute of Technology, Bangalore
 %[email protected]
  */

 #include
 #include
 #include

 #include
 #include
 using namespace std;

 void cvCompensationGlobal1(IplImage* _src,IplImage* dst)
 {
     static const int B=0;
     static const int G=1;
     static const int R=2;

     int width=_src->width;
     int height=_src->height;
     //double
     IplImage* src=cvCreateImage(cvGetSize(_src),IPL_DEPTH_64F,3);
     CvScalar minV=cvScalar(255,255,255,0);
     for (int h=0;h
         unsigned char* p=(unsigned char*)_src->imageData+h*_src->widthStep;
         double* pc=(double*)(src->imageData+h*src->widthStep);
         for (int w=0;w
             for (int i=0;i<3;i++) {
                 *pc=*p;
                 if (minV.val[i]>*pc) {
                     minV.val[i]=*pc;
                 }
                 pc++;
                 p++;
             }
         }
     }
     cvSubS(src,minV,src);

     int blackNum=0;
     double total=0;
     double acc[3]={0};
     for (int h=0;h
         double* p=(double*)(src->imageData+h*src->widthStep);
         for (int w=0;w
             if (p[0]<0.001&&p[1]<0.001&&p[2]<0.001) {
                 blackNum++;
                 p+=3;
                 continue;
             }
             double a=p[R];
             double b=p[R];
             if (p[B]
                 a=p[B];
             }else {
                 b=p[B];
             }
             if (p[G]
                 a=p[G];
             }else {
                 b=p[G];
             }
             total+=a+b;

             for (int i=0;i<3;i++) {
                 acc[i]+=p[i];
             }
             p+=3;
         }
     }
     double avgT=total/(2*(width*height-blackNum));
     CvScalar avg;
     IplImage* rgb[3];
     for (int i=0;i<3;i++) {
         rgb[i]=cvCreateImage(cvGetSize(src),IPL_DEPTH_64F,1);
         avg.val[i]=(double)acc[i]/(width*height);
         avg.val[i]=avgT/avg.val[i];
     }
     cvSplit(src,rgb[0],rgb[1],rgb[2],0);
     for (int i=0;i<3;i++) {
         cvScale(rgb[i],rgb[i],avg.val[i]);//bigger than 255
     }
     cvMerge(rgb[0],rgb[1],rgb[2],0,src);

     //y component only
     IplImage* y=cvCreateImage(cvGetSize(src),IPL_DEPTH_64F,1);
     for (int h=0;h
         double* psrc=(double*)(src->imageData+h*src->widthStep);
         double* py=(double*)(y->imageData+h*y->widthStep);
         for (int w=0;w
             *py++=psrc[R]*0.299+psrc[G]*0.587+psrc[B]*0.114;
             psrc+=3;
         }
     }
     double maxY=0;
     double minY=0;
     cvMinMaxLoc(y,&minY,&maxY);

     double sumY=0;
     //scale
     for (int h=0;h
         double* p=(double*)(y->imageData+h*y->widthStep);
         for (int w=0;w
             *p=(*p-minY)/(maxY-minY);
             sumY+=*p;
             p++;
         }
     }
     sumY*=255;
     sumY/=width*height;

     double scale=1.;
     if (sumY<64) {
         scale=1.4;
     }else if (sumY>192) {
         scale=0.6;
     }

     if (abs(scale-1.)>0.001) {
         for (int h=0;h
             double* psrc=(double*)(src->imageData+h*src->widthStep);
             unsigned char* pdst=(unsigned char*)dst->imageData+h*dst->widthStep;
             double t[3];
             for (int w=0;w
                 t[0]=pow(psrc[R],scale);
                 t[1]=pow(psrc[G],scale);
                 t[2]=psrc[B];
                 for (int i=0;i<3;i++) {
                     if (t[i]>255) {
                         pdst[i]=255;
                     }else {
                         pdst[i]=(unsigned char)t[i];
                     }
                 }
                 psrc+=3;
                 pdst+=3;
             }
         }
     }else{
         for (int h=0;h
             double* psrc=(double*)(src->imageData+h*src->widthStep);
             unsigned char* pdst=(unsigned char*)dst->imageData+h*dst->widthStep;
             for (int w=0;w
                 for (int i=0;i<3;i++) {
                     double t=*psrc++;
                     if (t>255) {
                         *pdst++=255;
                     }else {
                         *pdst++=(unsigned char)t;
                     }
                 }
             }
         }
     }

     //free memory
     cvReleaseImage(&src);
     cvReleaseImage(&y);
     for (int i=0;i<3;i++) {
         cvReleaseImage(&rgb[i]);
     }
 }

matlab 版，算法没问题，但代码写的不太好，我做了点修改

 %%%%%%%%%%%%%%%RGB normalisation%%%%%%%%%%%%%%%%%%%%%%
 %its cascaded implementain of 1 section of paper "A FAST SKIN REGION DETECTOR" by
 %Phil Chen, Dr.Christos Greecos
 %and
 %section 2.1 of paper "Simple and accurate face detection in color images" by
 %YUI TING PAI et al
 % Coding by Madhava.S.Bhat, Dept of Electronics an communication
 %Dr.Ambedkar Institute of Technology, Bangalore
 %[email protected]
 function[]= imag_improve_rgb(IMG)
 figure,imshow(IMG)
 title('original')
 R=double(IMG(:,:,1));
 G=double(IMG(:,:,2));
 B=double(IMG(:,:,3));
 [H,W]=size(R);

 % minR=0;
 % minG=0;
 % minB=0;
 % [srow,scol]=find(R==0 & G==0 & B==0);
 % if(isempty(srow) && isempty(scol))
     minR=min(min(R))
     minG=min(min(G))
     minB=min(min(B))
 % end
 R=R-minR;
 G=G-minG;
 B=B-minB;

 S=zeros(H,W);
 [srow,scol]=find(R==0 & G==0 & B==0);
 [sm,sn]=size(srow);

 for i=1:sm
      S(srow(i),scol(i))=1;
 end
 mstd=sum(sum(S))
 Nstd=(H*W)-mstd;

 Cst=0;
 Cst=double(Cst);
 for i=1:H
     for j=1:W
          a=R(i,j);
          b=R(i,j);

             if(B(i,j)
                a=B(i,j);
             else
                b=B(i,j);
             end

              if(G(i,j)
                 a=G(i,j);
              else
                 b=G(i,j);
              end

          Cst=a+b+Cst;

     end
 end
 %%%%sum of black pixels%%%%%%%%%%%
 blacksumR=0;
 blacksumG=0;
 blacksumB=0;
 for i=1:sm
     blacksumR=blacksumR+R(srow(i),scol(i));
     blacksumG=blacksumG+G(srow(i),scol(i));
     blacksumB=blacksumB+B(srow(i),scol(i));
 end
 Cstd = Cst/(2*Nstd)
 CavgR=sum(sum(R))./(H*W)
 CavgB=sum(sum(B))./(H*W)
 CavgG=sum(sum(G))./(H*W)
 Rsc=Cstd./CavgR
 Gsc=Cstd./CavgG
 Bsc=Cstd/CavgB

 R=R.*Rsc;
 G=G.*Gsc;
 B=B.*Bsc;

 C(:,:,1)=R;
 C(:,:,2)=G;
 C(:,:,3)=B;
 C=C/255;
 YCbCr=rgb2ycbcr(C);
 Y=YCbCr(:,:,1);

 figure,imshow(C)
 title('aft 1st stage of compensation')

 %normalize Y
 minY=min(min(Y));
 maxY=max(max(Y));
 Y=255.0*(Y-minY)./(maxY-minY);
 YEye=Y;
 Yavg=sum(sum(Y))/(W*H)

 T=1;
 if (Yavg<64)
     T=1.4
 elseif (Yavg>192)
     T=0.6
 end
 T

 if (T~=1)
     RI=R.^T;
     GI=G.^T;
 else
     RI=R;
     GI=G;
 end


 Cfinal(:,:,1)=uint8(RI);
 Cfinal(:,:,2)=uint8(GI);
 Cfinal(:,:,3)=uint8(B);
 figure,imshow(Cfinal)
 title('Light intensity compensated')

 % YCbCr=rgb2ycbcr(Cnew);