Does anyone know how to change the link on the image to be whatever is in [link] field within the same library? (I added a column/field called link). The link on the image is a link to the image, but I need this to be dictated by the link column. I have Sharepoint Designer open in the event I need to extend the web part, but I am not seeing that option.
This functionality is not included with the Picture Library Slideshow Web Part. Extending a web part requires your creating a custom web part in Visual Studio and inheriting from the OOB web part class. Unfortunately, it looks like the PictureLibrarySlideshowWebPart is sealed, so you not be able to inherit from it.
Picture Library SlideShow web part could be customized on the client side. In order accomplish it, we need to override the function for initializing picture in slideshow should be (see the code below).
The solution described below allows to specify custom url for picture link in Picture Library Slideshow web part.
Step 2. Add Content Editor web part (CEWP) on page where Slideshow web part is located and in the Content Editor tool pane, under Content Link, type /SiteAssets/SlideshowObjectInitializer.txt.
For more details about customizing Slideshow web part please follow this blog post