int i,j,k,l;

BYTE dt[1000][1000];

int M=pDoc->biHeader.biHeight;

int N=pDoc->biHeader.biWidth;

int h0[3][3]={{1,0,-1},{1,0,-1},{1,0,-1}};

int h1[3][3]={{0,-1,-1},{1,0,-1},{1,1,0}};

int h2[3][3]={{-1,-1,-1},{0,0,0},{1,1,1}};

int h3[3][3]={{-1,-1,0},{-1,0,1},{0,1,1}};

int h4[3][3]={{-1,0,1},{-1,0,1},{-1,0,1}};

int h5[3][3]={{0,1,1},{-1,0,1},{-1,-1,0}};

int h6[3][3]={{1,1,1},{0,0,0},{-1,-1,-1}};

int h7[3][3]={{1,1,0},{1,0,-1},{0,-1,-1}};

int x[8],max,d=80;

// tim diem co gia tri cao nhat

int lc=1;

int K=3;

// tao ban sao gt

for (i=0;i<M;i++)

for(j=0;j<N;j++)

dt[i][j]=pDoc->Data[i][j];

for (i=0;i<M;i++)

for(j=0;j<N;j++)

if (pDoc->Data[i][j]>d)

pDoc->Data[i][j]=255;

else pDoc->Data[i][j]=0;

//tinh lai cac diem phia trong

for(i=lc;i<M-lc;i++)

for(j=lc;j<N-lc;j++)

{

x[0]=x[1]=x[2]=x[3]=x[4]=x[5]=x[6]=x[7]=0;

for(k=0;k<=2*lc;k++)

for(l=0;l<=2*lc;l++)

{

x[0]+=h0[k][l]*dt[i-k+lc][j-l+lc];

x[1]+=h1[k][l]*dt[i-k+lc][j-l+lc];

x[2]+=h2[k][l]*dt[i-k+lc][j-l+lc];

x[3]+=h3[k][l]*dt[i-k+lc][j-l+lc];

x[4]+=h4[k][l]*dt[i-k+lc][j-l+lc];

x[5]+=h5[k][l]*dt[i-k+lc][j-l+lc];

x[6]+=h6[k][l]*dt[i-k+lc][j-l+lc];

 x[7]+=h7[k][l]*dt[i-k+lc][j-l+lc];

}

max=abs(x[0]);

for(k=1;k<8;k++)

if( max< abs(x[k]))

max= abs(x[k]);

if (max> d)

pDoc->Data[i][j]=255;

else

pDoc->Data[i][j]=0;

}

Invalidate();

}