Export Illustrator Vector Image From PDF Using C#

Question

I have a pdf that contains a vector image. I asked the client about it, and they said that they created the image in Illustrator and saved it as a pdf. Is there a way I can extract that image and convert it into a png? I've tried code from the following:

Extract image from PDF using itextsharp

http://www.vbforums.com/showthread.php?530736-2005-Extract-Images-from-a-PDF-file-using-iTextSharp

and a couple of other links that I can't find, but they all don't seem to work. My theory is that they are extracting embedded images like jpegs, bmps, pngs, etc., but what I am faced with is a direct export from illustrator.

Should I be using an illustrator sdk or is there a way for me to do it using itextsharp? Also, I need to convert it to a standard image format, like png, and send the stream to a calling app, so I'll need to be able to grab stream.

Answer 1

You will not be able to do this with iText, since it cannot render or rasterize vector graphics in PDF files.

Option 1:
If a GPL license works for you, you could rasterize your PDF file with Imagemagick+GNU Ghostscript, but AFAIK you will have to write the output into a file in this case.

Command line sample:

convert -density 300 -depth 8 c:\temp\mydoc.pdf c:\temp\myrasterimage.png

There is also a .net wrapper in Codeplex that might work for you: ImageMagick.NET

Option A:
If a commercial library is an option for you, you could try with Amyuni PDF Creator .Net. You can either use the method IacDocument.ExportToJpg, which requires writing into a file, or you can use the method IacDocument.DrawCurrentPage, which can be useful for writing the output into a memory stream.

Sample code for exporting one page using IacDocument.DrawCurrentPage into a memory stream:

const int twipsPerInch = 1440;
const int MM_ISOTROPIC = 7;
private static MemoryStream RasterizePDF(string filePath, int pageIndex, int targetDPI)
{
    Amyuni.PDFCreator.IacDocument doc = new Amyuni.PDFCreator.IacDocument();
    doc.SetLicenseKey("Evaluation", "07EFC00...77C23E29");
    FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);     
    doc.Open(fs, "");
    //Get the width and height of the target page
    Amyuni.PDFCreator.IacPageFormat format = doc.GetPage(pageIndex).GetPageFormat();
    doc.CurrentPageNumber = pageIndex;

    //Create Image
    Bitmap img = new Bitmap((int)(format.Width * targetDPI / twipsPerInch), (int)(format.Length * targetDPI / twipsPerInch), PixelFormat.Format32bppArgb);
    Graphics g = Graphics.FromImage(img);
    //set image object background to white
    g.Clear(Color.White);
    //Get a device context for the grahics object
    IntPtr hdc = g.GetHdc();
    SetMapMode(hdc, MM_ISOTROPIC);
    // set scaling factor
    SetWindowExtEx(hdc, twipsPerInch, twipsPerInch, 0);
    SetViewportExtEx(hdc, targetDPI, targetDPI, 0);
    //draw the contents of the PDF document on to the graphic context
    doc.DrawCurrentPage(hdc, false);
    //clean up
    g.ReleaseHdc(hdc);
    g.Dispose();
    // Save the bitmap as png into the resulting stream
    MemoryStream resultStrm = new MemoryStream();
    img.Save(resultStrm, ImageFormat.Png);
    //Prepare the stream to be read later on
    resultStrm.Position = 0;
}

[System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
private static extern int SetMapMode(IntPtr hdc, int MapMode);
[System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
private static extern int SetWindowExtEx(IntPtr hdc, int nXExtent, int nYExtent, int not_used);
[System.Runtime.InteropServices.DllImportAttribute("gdi32.dll")]
private static extern int SetViewportExtEx(IntPtr hdc, int nXExtent, int nYExtent, int not_used);

Disclaimer: I currently work as a developer of the library

Answer 2

Modern versions of AI uses PDF as an export format. It's an enhanced form of PDF containing important metadata for Illustrator but ultimately it is PDF.

Yes most PDF packages are aimed at extracting bitmaps as these come in atomic lumps. If your embedded image is vector then it's been dropped in in a format which most will not understand.

Illustrator may have used its own metadata to delimit the image. If this is the case then it will be difficult to extract. However it may have used a PDF analog like the Form XObject. If I was designing Illustrator I would probably do both.

So it probably is possible to extract though perhaps a little tricky. More is impossible to say without being able to see the document.

If you would like to mail your illustrator file to us at ABCpdf we will certainly see what we can suggest. :-)