public delegate Stream CreatePageStream(
	int pageNumber
)

Public Delegate Function CreatePageStream ( 
	pageNumber As Integer
) As Stream

public delegate Stream^ CreatePageStream(
	int pageNumber
)

type CreatePageStream = 
    delegate of 
        pageNumber : int -> Stream

CreatePageStream createDelegate = delegate (int pageNumber)
{
    var pagePath = System.IO.Path.Combine(@"C:\Temp", string.Format("page_{0}.png", pageNumber));
    return System.IO.File.Create(pagePath);
};
var previewOptions = new PreviewOptions(createDelegate);
previewOptions.PreviewFormat = PreviewOptions.PreviewFormats.PNG;
previewOptions.Height = 640;
previewOptions.Width = 480;
previewOptions.PageNumbers = new int[] { 1 };
using (var redactor = new Redactor("C:\Temp\SourceFile.pdf"))
{
    redactor.GeneratePreview(previewOptions);
}