You would not need an app - just some theme editing. Plenty of ways to handle it. One option would be to do something lie:
- Create a blog just for images posts. Let's call is "Photos"
- Add articles with a picture inside
- Blog page (/blogs/photos) loops over all the articles, grabbing the image and showing them in a nice grid / masonry layout
- Add the pinterest "pin all" code to blog page (/blogs/photos) so you can pin what picture you want from the page.
- If someone clicks on the image it will still take them to the article for further comment / like / reading action.
