Issues converting certain TIF compressions to PDF using iTextSharp - itext

Question

I am using iTextSharp to convert & stitch single-page TIF files to multi-page PDF file. The single-page TIF files are of different bit depths and compressions.
Here is the code-
private void button1_Click(object sender, EventArgs e)
{
List<string> TIFfiles = new List<string>();
Document document;
PdfWriter pdfwriter;
Bitmap tifFile;
pdfFilename = <file path>.PDF;
TIFfiles = <load the path to each TIF file in this array>;
//Create document
document = new Document();
// creation of the different writers
pdfwriter = PdfWriter.GetInstance(document, new System.IO.FileStream(pdfFilename, FileMode.Create));
document.Open();
document.SetMargins(0, 0, 0, 0);
foreach (string file in TIFfiles)
{
//load the tiff image
tifFile = new Bitmap(file);
//Total number of pages
iTextSharp.text.Rectangle pgSize = new iTextSharp.text.Rectangle(tifFile.Width, tifFile.Height);
document.SetPageSize(pgSize);
document.NewPage();
PdfContentByte cb = pdfwriter.DirectContent;
tifFile.SelectActiveFrame(FrameDimension.Page, 0);
iTextSharp.text.Image img = iTextSharp.text.Image.GetInstance(tifFile, ImageFormat.Tiff);
// scale the image to fit in the page
img.SetAbsolutePosition(0, 0);
cb.AddImage(img);
}
document.Close();
}
This code works well and stitches & converts tifs to PDF. Issue is with processing time and pdf file size that it creates when processing certain types of TIFs.
For e.g.
Original TIF --> B&W/Bit depth 1/Compression CCITT T.6 --> Faster processing, PDF file size is ~1.1x times the TIF file size.
Original TIF --> Color/Bit depth 8/Compression LZW --> Faster processing, PDF file size is ~1.1x times the TIF file size.
Original TIF --> Color/Bit depth 24/Compression JPEG--> Slow processing, PDF file size is ~12.5x times the TIF file size.
Why doesn't converting Color/Bit depth 24/Compression JPEG files gives similar result as other tif files?
Moreover, this issue is only with iTextSharp. I had a colleague test the same set of TIF samples using Java-iText and the resulting PDF was of smaller size (1.1x times) and had faster processing.
Unfortunately, I need to use .Net for this TIF to PDF conversion, so am stuck with using iTextSharp.
Any ideas/suggestions on how to get those Compression JPEG TIF files to create smaller size PDFs as it does for other TIF compressions?
Appreciate your help!
Regards,
AG

Answer 1

I was able to reproduce your problem with the code you supplied, but found that the problem went away once I used Image.GetInstance instead of the bitmap used in your sample. When using the code below, the file size and run time was the same between Java and C#. If you have any questions about the sample, don't hesitate to ask.
List<string> TIFfiles = new List<string>();
Document document;
PdfWriter pdfwriter;
iTextSharp.text.Image tifFile;
String pdfFilename = pdfFile;
TIFfiles = new List<string>();
TIFfiles.Add(tifFile1);
TIFfiles.Add(tifFile2);
TIFfiles.Add(tifFile3);
TIFfiles.Add(tifFile4);
TIFfiles.Add(tifFile5);
TIFfiles.Add(tifFile6);
TIFfiles.Add(tifFile7);
//Create document
document = new Document();
// creation of the different writers
pdfwriter = PdfWriter.GetInstance(document, new System.IO.FileStream(pdfFilename, FileMode.Create));
document.Open();
document.SetMargins(0, 0, 0, 0);
int i = 0;
while (i < 50)
{
foreach (string file in TIFfiles)
{
//load the tiff image
tifFile = iTextSharp.text.Image.GetInstance(file);
//Total number of pages
iTextSharp.text.Rectangle pgSize = new iTextSharp.text.Rectangle(tifFile.Width, tifFile.Height);
document.SetPageSize(pgSize);
document.NewPage();
PdfContentByte cb = pdfwriter.DirectContent;
// scale the image to fit in the page
tifFile.SetAbsolutePosition(0, 0);
cb.AddImage(tifFile);
}
i++;
}
document.Close();