将图像适配到PictureBox中

using (SqlConnection myDatabaseConnection = new SqlConnection(myConnectionString.ConnectionString))
{
    myDatabaseConnection.Open();
    using (SqlCommand SqlCommand = new SqlCommand("Select Photo from Employee where EmpID LIKE '%' + @EmpID + '%' ", myDatabaseConnection))
    {
        SqlCommand.Parameters.AddWithValue("@EmpID", textBox1.Text);
        var DS = new DataSet();
        var adapter = new SqlDataAdapter(SqlCommand);
        adapter.Fill(DS, "Images");

        var imagesTable = DS.Tables["Images"];
        var imagesRows = imagesTable.Rows;
        var count = imagesRows.Count;

        if (count <= 0) return;

        var imageColumnValue =
            imagesRows[count - 1]["Image"];
        if (imageColumnValue == DBNull.Value)
            return;

        var data = (Byte[])imageColumnValue;
        using (var stream = new MemoryStream(data))
        {
            pictureBox1.Image = Image.FromStream(stream);
        }

    }
}

如果图片太大无法适应picturebox，需要什么代码才能让图片适应picturebox？
我的picturebox是正方形的，如果图片是矩形的，如何裁剪并在picturebox中显示它，就像这张图片一样，图片的下部分将被裁剪。