Sometimes we receive problematic PDFs that require rebuilding before we annotate them in our application. The root cause is generally that the PDF was created in some anomalous way that plays havoc with image rotation and the like. The quickest and easiest fix, within Acrobat, is to either use the Print to PDF option, and import the new PDF or, in extreme cases, export the PDF to an image and then create a new PDF from those images.
When doing this in Acrobat, the file sizes increase somewhat for certain PDFs, mostly ones that are scanned images of documents. However, when doing the same operation (PDF to TIFF to PDF) with Syncfusion, the file sizes dramatically increase in size, sometimes by a factor of 6 or 10.
The only direction I can find in the documentation is to reduce the image quality of the source TIFF files, but this degradation of quality is not acceptable. Is there some other option that I am not seeing that we can use to rebuild these PDFs while maintaining some semblance of the original PDF file size?
This is the code that we are using to export the PDF and then build a new one:
public List<string> ExportPDFToTiff(string pathToPDF)
{
List<string> tiffPaths = new List<string>();
var tiffCreationThread = new Thread(() =>
{
var pdfViewerControl = new PdfViewerControl();
try
{
//Load the input PDF file
using (var loadedDocument = new PdfLoadedDocument(pathToPDF))
{
try
{
pdfViewerControl.Load(loadedDocument);
//Export all the pages as images
BitmapSource[] images = pdfViewerControl.ExportAsImage(0, loadedDocument.Pages.Count - 1);
//Set up the output path
string outputDirectory = Path.Combine(Path.GetTempPath(), "PdfConversion");
Directory.CreateDirectory(outputDirectory);
if (images != null)
{
for (int i = 0; i < images.Length; i++)
{
//Initialize the new Tiff bitmap encoder
var encoder = new TiffBitmapEncoder();
//Create the bitmap frame using the bitmap source and add it to the encoder
encoder.Frames.Add(BitmapFrame.Create(images[i]));
//Create the file stream for the output in the desired image format
string tiffPath = Path.Combine(outputDirectory, i.ToString() + ".tiff");
tiffPaths.Add(tiffPath);
using (FileStream stream = new FileStream(tiffPath, FileMode.Create))
{
//Save the stream, so that the image will be generated in the output location
encoder.Save(stream);
}
}
}
pdfViewerControl.Unload(true);
}
catch (Exception ex)
{
Debug.Write("Error: " + ex.Message);
}
}
}
finally
{
pdfViewerControl = null;
}
});
tiffCreationThread.SetApartmentState(ApartmentState.STA);
tiffCreationThread.Start();
tiffCreationThread.Join();
return tiffPaths;
}
public void CreatePDFFromTiffs(List<string> pathsToTiffs, PdfDocument newPdfDoc)
{
Debug.WriteLine("Begin Create PDF from Tiffs...");
var currentPage = 1;
foreach (var tiffPath in pathsToTiffs)
{
var image = new PdfBitmap(tiffPath);
// Create a new section and a new page with the dimensions of the TIFF image
PdfSection section = newPdfDoc.Sections.Add();
section.PageSettings.Size = new SizeF(image.Width, image.Height);
section.PageSettings.Margins.All = 0;
if (image.Width > image.Height)
{
section.PageSettings.Orientation = PdfPageOrientation.Landscape;
}
else
{
section.PageSettings.Orientation = PdfPageOrientation.Portrait;
}
PdfPage page = section.Pages.Add();
Debug.WriteLine("Added page " + currentPage);
currentPage++;
// Draw the image on the PDF page
page.Graphics.DrawImage(image, 0, 0, image.Width, image.Height);
}
}
