From DreamSys Software:
The DreamSys PDF API is a DLL that can convert TIFF images into a PDF. You can create multiple chapters (PDF Section) to organize your images; this will create bookmarks in the PDF to link to specific pages. The API is written in C++, but can be used in an application written in C, C++, C#, VB, Java or any other language that allows you to import functions from a DLL. The API will not load the actual TIFF data into memory until it is time to write that TIF to the file, so it can handle very large PDFs while using very little memory. This API is also thread safe, you can create multiple PDFs on separate threads and they will not conflict.