#include <stdio.h>
#include "cv.h"
#include "cxcore.h"
#include "highgui.h"
#pragma comment(lib,"cv.lib")
#pragma comment(lib,"cxcore.lib")
#pragma comment(lib,"highgui.lib")

#define KIDO_SIZE 256
#define GRAPH_HEIGHT 512

void histgram(unsigned int *out, unsigned char *in, int inHeight, int inWidth, int inChannel);

int main(){
   IplImage *in, *graph;
   unsigned int *outData;
   int i,j;
   double maxRate;
   
   in = cvLoadImage("./image640.bmp", 0);
   graph = cvCreateImage(cvSize(KIDO_SIZE, GRAPH_HEIGHT), in->depth, in->nChannels);
   
   outData = (unsigned int *)malloc(sizeof(unsigned int) * (KIDO_SIZE + 1));

   // 0初期化
   memset(outData, 0, sizeof(unsigned int) * (KIDO_SIZE + 1));
   histgram(outData, (unsigned char*)in->imageData, in->height, in->width, in->nChannels);

   // 最大数の要素の値がグラフの最大値に来るように調整
   maxRate = (double)graph->height / (double)outData[KIDO_SIZE];

   for(i = 0; i < KIDO_SIZE; ++i){
       cvLine(graph, cvPoint(i, graph->height - outData[i] * maxRate), cvPoint(i, graph->height), CV_RGB(255, 255, 255), 1);
   }

   cvNamedWindow("in", 1);
   cvShowImage("in", in);
   cvNamedWindow("graph", 1);
   cvShowImage("graph", graph);
   cvWaitKey(-1);

   cvDestroyWindow("in");
   cvDestroyWindow("graph");
   
   cvReleaseImage( &in );
   cvReleaseImage( &graph );
   
   free(outData);


   return 0;
}


void histgram(unsigned int *out, unsigned char *in, int inHeight, int inWidth, int inChannel){
    int i, j;
    int index;

    for(i = 0; i < inHeight; ++i){
        for(j = 0; j < inWidth; ++j){
            // 入力画像の輝度値と等しい配列番号の要素をインクリメント
            index = in[i * inWidth + j];
            ++out[ index ];

            // 最大値を格納する
            if(out[KIDO_SIZE] < out[ index ]){
                out[KIDO_SIZE] = out[ index ];
            }
        }
    }
}