public static class BoundingBoxConverter
    {
        public static Rectangle ToDevBox(this PdfPageObject pageObj, PdfPage page)
        {
            var pt1 = page.PageToDevice(0, 0, Convert.ToInt32(page.Width), Convert.ToInt32(page.Height), PageRotate.Normal, pageObj.BoundingBox.Left, pageObj.BoundingBox.Top);
            var pt2 = page.PageToDevice(0, 0, Convert.ToInt32(page.Width), Convert.ToInt32(page.Height), PageRotate.Normal, pageObj.BoundingBox.Right, pageObj.BoundingBox.Bottom);

            //Build rectangle
            var rect = new Rectangle(pt1.X, pt1.Y, pt2.X - pt1.X, pt2.Y - pt1.Y);
            //And  normalize it if it has the negative size in any dimension
            if (rect.Width < 0)
            {
                rect.Width = -rect.Width;
                rect.X -= rect.Width;
            }
            if (rect.Height < 0)
            {
                rect.Height = -rect.Height;
                rect.Y -= rect.Height;
            }

            return rect;
        }
    }