private static void HandleReplaceImage(object sender, PdfReplaceImageEventArgs e)
        {
            if (e.OldImageID.Value == "/Im1")
            {
                // Replace the existing image with a checkers board.
                MemoryStream checkers = new MemoryStream(new byte[] { 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0 });
                PdfRawImage rawImage = new PdfRawImage(checkers);
                rawImage.Width = 5;
                rawImage.Height = 5;
                rawImage.BitsPerComponent = 8;
                rawImage.ColorSpace = new PdfGrayColorSpace();

                e.NewImage = rawImage;
            }
            else
            {
                if (e.OldImageID.Value == "/Im2")
                {
                    // Remove the image from the page by setting the new image (the replacement image) to null.
                    e.NewImage = null;
                }
            }
        }
        private static void HandleReplaceImage(object sender, PdfReplaceImageEventArgs e)
        {
            if (e.OldImageID.Value == "/Im1")
            {
                // Replace the existing image with a checkers board.
                MemoryStream checkers = new MemoryStream(new byte[] { 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0, 255, 0 });
                PdfRawImage  rawImage = new PdfRawImage(checkers);
                rawImage.Width            = 5;
                rawImage.Height           = 5;
                rawImage.BitsPerComponent = 8;
                rawImage.ColorSpace       = new PdfGrayColorSpace();

                e.NewImage = rawImage;
            }
            else
            {
                if (e.OldImageID.Value == "/Im2")
                {
                    // Remove the image from the page by setting the new image (the replacement image) to null.
                    e.NewImage = null;
                }
            }
        }