Convert PDF to Images formats using C#

Aspose.PDF for .NET uses several approaches to convert PDF to image. Generally speaking, we use two approaches: conversion using the Device approach and conversion using SaveOption. This section will show you how to convert PDF documents to image formats such as BMP, JPEG, GIF, PNG, EMF, TIFF, and SVG formats using one of those approaches.

There are several classes in the library that allow you to use a virtual device to transform images. DocumentDevice is oriented for conversion whole document, but ImageDevice - for a particular page.

Convert PDF using DocumentDevice class

Aspose.PDF for .NET makes a possible to convert PDF Pages to TIFF images.

The TiffDevice (based on DocumentDevice) class allows you to convert PDF pages to TIFF images. This class provides a method named Process which allows you to convert all the pages in a PDF file to a single TIFF image.

Convert PDF Pages to One TIFF Image

Aspose.PDF for .NET explain how to convert all pages in a PDF file to a single TIFF image:

  1. Create an object of the Document class.
  2. Call the Process method to convert the document.
  3. To set the output file’s properties, use the TiffSettings class.

The following code snippet shows how to convert all the PDF pages to a single TIFF image.

public static void ConvertPDFtoTIFF()
{
    // Open document
    Document pdfDocument = new Document(_dataDir + "PageToTIFF.pdf");

    // Create Resolution object
    Resolution resolution = new Resolution(300);

    // Create TiffSettings object
    TiffSettings tiffSettings = new TiffSettings
    {
        Compression = CompressionType.None,
        Depth = ColorDepth.Default,
        Shape = ShapeType.Landscape,
        SkipBlankPages = false
    };

    // Create TIFF device
    TiffDevice tiffDevice = new TiffDevice(resolution, tiffSettings);

    // Convert a particular page and save the image to stream
    tiffDevice.Process(pdfDocument, _dataDir + "AllPagesToTIFF_out.tif");
}

Convert One Page to TIFF Image

Aspose.PDF for .NET allows to convert a particular page in a PDF file to a TIFF image, use an overloaded version of the Process(..) method which takes a page number as an argument for conversion. The following code snippet shows how to convert the first page of a PDF to TIFF format.

public static void ConvertPDFtoTiffSinglePage()
{
    // Open document
    Document pdfDocument = new Document(_dataDir + "PageToTIFF.pdf");

    // Create Resolution object
    Resolution resolution = new Resolution(300);

    // Create TiffSettings object
    TiffSettings tiffSettings = new TiffSettings
    {
        Compression = CompressionType.None,
        Depth = ColorDepth.Default,
        Shape = ShapeType.Landscape,
    };

    // Create TIFF device
    TiffDevice tiffDevice = new TiffDevice(resolution, tiffSettings);

    // Convert a particular page and save the image to stream
    tiffDevice.Process(pdfDocument, 1, 1, _dataDir + "PageToTIFF_out.tif");
}

Use Bradley algorithm during conversion

Aspose.PDF for .NET has been supporting the feature to convert PDF to TIF using LZW compression and then with the use of AForge, Binarization can be applied. However one of the customers requested that for some images, they need to get the Threshold using Otsu, so they also would like to use Bradley.

  public static void ConvertPDFtoTiffBradleyBinarization()
{
     // Open document
     Document pdfDocument = new Document(_dataDir + "PageToTIFF.pdf");

    string outputImageFile = _dataDir + "resultant_out.tif";
    string outputBinImageFile = _dataDir + "37116-bin_out.tif";

    // Create Resolution object
    Resolution resolution = new Resolution(300);
    // Create TiffSettings object
    TiffSettings tiffSettings = new TiffSettings
    {
        Compression = CompressionType.LZW,
        Depth = Aspose.Pdf.Devices.ColorDepth.Format1bpp
    };
    // Create TIFF device
    TiffDevice tiffDevice = new TiffDevice(resolution, tiffSettings);
    // Convert a particular page and save the image to stream
    tiffDevice.Process(pdfDocument, outputImageFile);

    using (FileStream inStream = new FileStream(outputImageFile, FileMode.Open))
    {
        using (FileStream outStream = new FileStream(outputBinImageFile, FileMode.Create))
        {
            tiffDevice.BinarizeBradley(inStream, outStream, 0.1);
        }
    }
} 

Convert PDF using ImageDevice class

ImageDevice is the ancestor for BmpDevice, JpegDevice, GifDevice, PngDevice and EmfDevice.

  • The BmpDevice class allows you to convert PDF pages to BMP images.
  • The EmfDevice class allows you to convert PDF pages to EMF images.
  • The JpegDevice class allows you to convert PDF pages to JPEG images.
  • The PngDevice class allows you to convert PDF pages to PNG images.
  • The GifDevice class allows you to convert PDF pages to GIF images.

Let’s take a look at how to convert a PDF page to an image.

BmpDevice class provides a method named Process which allows you to convert a particular page of the PDF file to BMP image format. The other classes have the same method. So, if we need to convert a PDF page to an image, we just instantiate the required class.

The following code snippet shows this possibility:

public static class ExampleConvertPdfToImage
{
     private static readonly string _dataDir = @"C:\Samples\";
    // BMP, JPEG, GIF, PNG, EMF
    public static void ConvertPDFusingImageDevice()
    {
        // Create Resolution object            
        Resolution resolution = new Resolution(300);
        BmpDevice bmpDevice = new BmpDevice(resolution);
        JpegDevice jpegDevice = new JpegDevice(resolution);
        GifDevice gifDevice = new GifDevice(resolution);
        PngDevice pngDevice = new PngDevice(resolution);
        EmfDevice emfDevice = new EmfDevice(resolution);

        Document document = new Document(_dataDir + 
            "ConvertAllPagesToBmp.pdf");
            
        ConvertPDFtoImage(bmpDevice, "bmp", document);
        ConvertPDFtoImage(jpegDevice,"jpeg", document);
        ConvertPDFtoImage(gifDevice, "gif", document);
        ConvertPDFtoImage(pngDevice, "png", document);
        ConvertPDFtoImage(emfDevice, "emf", document);
            
    }
}

public static void ConvertPDFtoImage(ImageDevice imageDevice, 
        string ext, Document pdfDocument)
{
    for (int pageCount = 1; pageCount <= pdfDocument.Pages.Count; pageCount++)
    {
        using (FileStream imageStream = 
        new FileStream($"{_dataDir}image{pageCount}_out.{ext}", 
        FileMode.Create))
        {
            // Convert a particular page and save the image to stream
            imageDevice.Process(pdfDocument.Pages[pageCount], imageStream);

            // Close stream
            imageStream.Close();
        }
    }
}

Convert PDF using SaveOptions class

This part of article shows you how to convert PDF to SVG using C# and SaveOptions class.

Scalable Vector Graphics (SVG) is a family of specifications of an XML-based file format for two-dimensional vector graphics, both static and dynamic (interactive or animated). The SVG specification is an open standard that has been under development by the World Wide Web Consortium (W3C) since 1999.

SVG images and their behaviors are defined in XML text files. This means that they can be searched, indexed, scripted and if required, compressed. As XML files, SVG images can be created and edited with any text editor, but it is often more convenient to create them with drawing programs such as Inkscape.

Aspose.PDF for .NET supports the feature to convert SVG image to PDF format and also offers the capability to convert PDF files to SVG format. To accomplish this requirement, the SvgSaveOptions class has been introduced into the Aspose.PDF namespace. Instantiate an object of SvgSaveOptions and pass it as a second argument to the Document.Save(..) method.

The following code snippet shows the steps for converting a PDF file to SVG format with .NET.

public static void ConvertPDFtoSVG()
{
    // Load PDF document
    Document document = new Document(System.IO.Path.Combine(_dataDir, "input.pdf"));
    // Instantiate an object of SvgSaveOptions
    SvgSaveOptions saveOptions = new SvgSaveOptions
    {
        // Do not compress SVG image to Zip archive
        CompressOutputToZipArchive = false,
        TreatTargetFileNameAsDirectory = true                
    };
            
    // Save the output in SVG files
    document.Save(System.IO.Path.Combine(_dataDir, "PDFToSVG_out.svg"), saveOptions);
}