private int _writedImageIndex = 0;

public void ExtractAllImages()
{
    //Initialize the SDK library
    //You have to call this function before you can call any PDF processing functions.
    PdfCommon.Initialize();

    //Open and load a PDF document from a file.
    using (var doc = PdfDocument.Load(@"c:\test001.pdf"))
    {
        //Enumerate all pages sequentially in a given document
        foreach (var page in doc.Pages)
        {
            //Extract and save images
            ExtractImagesFromPage(page);

            //dipose page object to unload it from memory
            page.Dispose();
        }
    }

    //Release all resources allocated by the SDK library
    PdfCommon.Release();
}

private void ExtractImagesFromPage(PdfPage page)
{
    //Enumerate all objects on a page
    foreach (var obj in page.PageObjects)
    {
        var imageObject = obj as PdfImageObject;
        if (imageObject == null)
            continue; //if not an image object then nothing do

        //Save image to disk
        var path = string.Format(@"c:\\Images\\image_{0}.png", ++_writedImageIndex);
        imageObject.Bitmap.Image.Save(path, ImageFormat.Png);
    }
}

private BitmapSource CreateGdiBitmap(PdfBitmap bitmap)
{
    //Determine pixel format
    PixelFormat pixelFormat = ...
    switch (bitmap.Format)
    {
        case BitmapFormats.FXDIB_Rgb: pixelFormat = wpf_pixel_format
        case BitmapFormats.FXDIB_Rgb32: pixelFormat = wpf_pixel_format
        case BitmapFormats.FXDIB_Argb: pixelFormat = wpf_pixel_format
    }

    //Create a Gdi+ bitmap
    return BitmapSource.Create(bitmap.Width, bitmap.Height, 96, 96, pixelFormat, null, bitmap.Buffer, bitmap.Stride*bitmap.Height, bitmap.Stride);
}