Examples-GroupDocs.Annotation.Examples.CSharp-GroupDocs.AnnotationExamples-PDFAnnotation-GetThumnailsOfPagesForPDF.cs

// For complete examples and data files, please go to https://github.com/groupdocs-annotation/GroupDocs.Annotation-for-.NET
// Create instance of annotator. 
AnnotationConfig cfg = CommonUtilities.GetConfiguration();
AnnotationImageHandler annotator = new AnnotationImageHandler(cfg);
// Get input file stream
Stream inputFile = new FileStream(CommonUtilities.MapSourceFilePath(CommonUtilities.filePath), FileMode.Open, FileAccess.ReadWrite);
List<PageImage> images = annotator.GetPages(inputFile, new ImageOptions { WithoutAnnotations = true });          
//Then if we want get thumbnail we call GetThumbnail() method of PageImage item:
foreach (PageImage pageImage in images)
{
    Stream stream = pageImage.GetThumbnail(); // do something with stream 
}
// Default image size was 300x180. If need specified image size, you can pass method parameters:
// image thumbnails 100x100
foreach (PageImage pageImage in images)
{
    Stream stream = pageImage.GetThumbnail(100, 100);
    // do something with stream 
}