This is very simple and easy code to select only images files
OpenFileDialog openFileDialog = new OpenFileDialog();
openFileDialog.Filter = "Images *.jpg; *.jpeg; *.gif; *.png; *.bmp; *.tif, *.tiff; | *.jpg; *.jpeg; *.gif; *.png; *.bmp; *.tif, *.tiff;";
if(openFileDialog.ShowDialog() == DialogResult.OK)
{
imgBox.Image = new Bitmap(openFileDialog.FileName);
}
else
{
MessageBox.Show("Some thing went wrong");
}