I don't have a need to pull images, description etc from a PDF file.
If this is online web based, I may try it for the fun of it.
Not interested if this is app because I don't like installing unnecessary app into my phone or unnecessary software into my computer.
If your goal is to make money through ads, you can still make money from ads on a web-based software. For example, this web-based image resizer (
http://www.picresize.com/), I used it a lot. No software to install. The author made money from the ads.
If you want some ideas about what is in demand, it is a
online 1080P YouTube downloader. There are plenty of online (web-based) 720P YouTube downloader on the web but few or none online 1080P YouTube downloader exists in the market. Those that claim to download 1080P usually downloads a 1080P video without audio.