Have you had a look at http://www.livedocx.com/? I’ve used it to convert DOC files on the fly and it works like a treat. The free version allows 200 conversions/day (I think). The basic idea would be to create an html file (that’s the easiest format, I think) in your controller and pass the HTML file to the LiveDocX API.
The only downside to the free version is the font limitations. If you need to convert/embed text into your PDF, your only choices for fonts are those installed on their servers.
@jiaming Can you please correct the thread title? I find it personally misleading, you’re talking about uploading pics and converting the result to pdf, and in further posts, you’re talking about converting doc and ppt…
Im not sure you still need any help or not, here is a professional pdf programming source, including pdf to image converting, you can get some online help or just try the free tial version to get some experience to start your own programming.
One approach would be to create some HTML with all of the images in it then pass it to a HTML to PDF service like GrabzIt’s. You would then get all of the images in a single PDF. There is a free tier you can use as well.
For the purposes of full disclosure, I am the creator of this service!