Mat src_gray;
cvtColor( src, src_gray, CV_BGR2GRAY );

System::Drawing::Graphics^ graphics = pictureBox1->CreateGraphics();
System::IntPtr ptr(src.ptr());
System::Drawing::Bitmap^ b  = gcnew System::Drawing::Bitmap(src.cols,src.rows,src.step,System::Drawing::Imaging::PixelFormat::Format24bppRgb,ptr);
System::Drawing::RectangleF rect(0,0,control->Width,control->Height);
graphics->DrawImage(b,rect);

System::Drawing::Bitmap^ b  = gcnew System::Drawing::Bitmap(grayImage.cols,grayImage.rows,grayImage.step,System::Drawing::Imaging::PixelFormat::Format8bppIndexed,ptr);