pictureBox1.SizeMode = PictureBoxSizeMode.Zoom;//加载的图片自适应picrurebox大小
//创建OpenFileDialog
OpenFileDialog opnDlg = new OpenFileDialog();
//为图像选择一个筛选器
opnDlg.Filter = "所有图像文件|*.bmp;*.pcx;*.png;*.jpg;*.gif;" +
"*.tif;*.ico;*.dxf;*.cgm;*.cdr;*.wmf;*.eps;*.emf|" +