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

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

int main(){
    IplImage *in, *out;

    in = cvLoadImage("./image.bmp", 0);
    out = cvCreateImage(cvSize(in->width, in->height), in->depth, in->nChannels);
    
    laplacian((unsigned char*)out->imageData, (unsigned char*)in->imageData, in->height, in->width, in->nChannels);

    cvNamedWindow("in", 1);
    cvShowImage("in", in);
    cvNamedWindow("out", 1);
    cvShowImage("out", out);
    cvWaitKey(-1);
    
    cvDestroyWindow("in");
    cvDestroyWindow("out");

    cvReleaseImage( &in );
    cvReleaseImage( &out );

    return 0;
}

void laplacian(unsigned char *out, unsigned char *in, int inHeight, int inWidth, int inChannel){
    int i, j, k, l;
    int weight[9] = {2,  0,  2,
        0, -8,  0,
        2,  0,  2};
    int *imgTmp;
    int weightSize = 3;

    int start = -1;
    int end = start + weightSize;
    double dataTmp;

    int widthStep;

    widthStep = inWidth * inChannel;
    if(widthStep % 4 != 0){
        widthStep = widthStep + 4 - widthStep % 4;
    }
    for(i = 1; i < (inHeight - 1); ++i){
        for(j = 1; j < (inWidth - 1); ++j){
            dataTmp = 0;
            for(k = start; k < end; ++k){
                for(l = start; l < end; ++l){
                    dataTmp += weight[(k - start) * weightSize + (l - start)] * (unsigned char)in[(i + k) * widthStep + (j + l)];

                }
            }

            // 255を超えた値は255、0未満の値は絶対値にする
            if(dataTmp > 255){
                dataTmp = 255;
            } else if(dataTmp < 0){
                dataTmp = -dataTmp;
            }
            out[i * widthStep + j] = dataTmp;
        }
    }
}