Using GroupDocs.Conversion for .NET, it is possible to convert any PDF document to HTML file in C#. Conversion process or feature is not limited to PDF files only. You can convert any supported file format to HTML.
GroupDocs.Conversion for .NET is a back-end API that can be integrated in any (new or existing) .NET application.
C# Example: How to Convert a PDF to HTML
This API can convert any source document to a markup format which in general is an HTML conformable format.
You can see that sample PDF has some visuals and text. And the resultant HTML covers everything.