Анотирайте DOT от Net

//Add text field annotation to the document from local disk
using (Annotator annotator = new Annotator("input.bmp"))
{
    TextFieldAnnotation textField = new TextFieldAnnotation
    {
        BackgroundColor = 65535,
        Box = new Rectangle(100, 100, 100, 100),
        CreatedOn = DateTime.Now,
        Text = "Some text",
        FontColor = 65535,
        FontSize = 12,
        Message = "This is text field annotation",
        Opacity = 0.7,
        PageNumber = 0,
        PenStyle = PenStyle.Dot,
        PenWidth = 3,
        FontFamily = "Arial",
        TextHorizontalAlignment = HorizontalAlignment.Center,
        Replies = new List
        {
            new Reply
            {
                Comment = "First comment",
                RepliedOn = DateTime.Now
            },
            new Reply
            {
                Comment = "Second comment",
                RepliedOn = DateTime.Now
            }
        }
    };
    annotator.Add(textField);
    annotator.Save("result.bmp");
}

// 1- How to remove annotation from document using annotation index

using (Annotator annotator = new Annotator("result.bmp"))
{
    annotator.Remove(0);
    annotator.Save("removed.bmp");
}

// 2- How to remove annotation from document using annotation object

using (Annotator annotator = new Annotator("result.bmp"))
{
    var tmp = annotator.Get();
    annotator.Remove(tmp[0]);
    annotator.Save("removed.bmp");
}

// 3- How to remove some annotations from document using list of ID’s

using (Annotator annotator = new Annotator("result.bmp"))
{
    var idList = new List{1, 2, 3};
    annotator.Remove(idList);
    annotator.Save("removed.bmp");
}

// 4- How to remove some annotations from document using list of annotations

using (Annotator annotator = new Annotator("result.bmp"))
{
    var tmp = annotator.Get();
    annotator.Remove(tmp);
    annotator.Save("removed.bmp");
}

// open annotated document
using (Annotator annotator = new Annotator("result.bmp"))
{
    //assuming we are going to change some properties of existing annotation
        AreaAnnotation updated = new AreaAnnotation
            {
                    // It's important to set existed annotation Id
                    Id = 1,
                    BackgroundColor = 255,
                    Box = new Rectangle(0, 0, 50, 200),
                    CreatedOn = DateTime.Now,
                    Message = "This is updated annotation",
                    Replies = new List
                    {
                        new Reply
                        {
                            Comment = "Updated first comment",
                            RepliedOn = DateTime.Now
                        },
                        new Reply
                        {
                            Comment = "Updated second comment",
                            RepliedOn = DateTime.Now
                        }
                    }
                };
        // update annotation
        annotator.Update(updated);
        annotator.Save("result.bmp");
}

// for using this example input file ("annotated.bmp") must be with annotations
using (Annotator annotator = new Annotator("annotated.bmp"))
{
    List annotations = annotator.Get();
    XmlSerializer formatter = new XmlSerializer(typeof(List));
    using (FileStream fs = new FileStream("annotations.xml", FileMode.Create))
    {
        fs.SetLength(0);
        formatter.Serialize(fs, annotations);
    }
}