Relating content (using tags, category) in the gallery to a blog post topic (tags, category)

Hi guys, we created a sidebar with a slideshow image gallery that displays a selection of automatic rotating images buy I would prefer to display certain related images from the imagery gallery depending on blog topic (probably by category/tag of the blog being read- in other word relate the gallery images displayed to the blog post topic being read

So, if someone is reading and article on an Electric Bike as in this example - the images displayed in the side bar are on electric bikes or related subjects.

Thanks so much for any ideas!

Categories and tags are available only for events, blog posts, and products, not for images or image galleries unless they are in a blog post.  The only way I can think of to make what you want is to create a gallery in each post with the associated images. You can put the gallery on the side of the post with a bit of design manipulation.