1.Thay Đổi Độ Tương Phản

         int M=pDoc->biHeader.biHeight;

          int N=pDoc->biHeader.biWidth;

          int m,n,u;

          float LUT[256];

          int a=80,Va=120,b=255,Vb=255;

          int L=255;

     for(u=0;u<=L;u++)

          {        if(u<=a)

                             LUT[u]=(u*Va/a);

                   else if(u<b)

                             LUT[u]=Va+(u-a)*(Vb-Va+1)/(b-a+1);

                   else

                             LUT[u]=Vb+(u-b)*(L-Vb+1)/(L-b+1);

          }

          for(m=0;m<M;m++)

                   for(n=0;n<N;n++)

                   {

                             pDoc->Data[m][n]=LUT[pDoc->Data[m][n]];

                             }

          Invalidate();

          }