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Export Images from PDF created with pdfsharp
https://forum.pdfsharp.net/viewtopic.php?f=2&t=2146		 Page 1 of 1
Author:  xeo [ Thu Sep 20, 2012 9:51 am ]
Post subject:  Export Images from PDF created with pdfsharp
Hello,
I am trying to use the export image example to export images from a pdf.
The pdf was created with pdfsharp, basically it contains only jpeg images created with this code:
Code:
PdfPage page = document.AddPage();
page.Size = PageSize.A4;
XGraphics gfx = XGraphics.FromPdfPage(page);
using (XImage image = XImage.FromFile(imageFile))
{
   gfx.DrawImage(image, 0, 0, page.Width, page.Height);
   }


When I run the code sample I get an exception in this method:

Code:
static void ExportImage(PdfDictionary image, ref int count)
        {
            string filter = image.Elements.GetName("/Filter");
            switch (filter)
            {
                case "/DCTDecode":
                    ExportJpegImage(image, ref count);
                    break;
                /*case "/FlateDecode":
                    ExportAsPngImage(image, ref count);
                    break;*/
            }
        }


when it tries to read the filter it says object is not a string.

Any advice?
Thank you
Author:  Thomas Hoevel [ Thu Sep 20, 2012 12:17 pm ]
Post subject:  Re: Export Images from PDF created with pdfsharp
Hi!
Sometimes PDFsharp (and other tools) use both "/FlateDecode" and "/DCTDecode" if this uses less space than only "/DCTDecode". This is a new feature for PDFsharp and the Export sample does not implement this.

You have to call Decode from the FlateDecode class before saving the JPEG file if both filters are specified.
See also:
viewtopic.php?p=5600#p5600
Author:  xeo [ Fri Sep 21, 2012 6:08 am ]
Post subject:  Re: Export Images from PDF created with pdfsharp
thank you it works like a charm!
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