This is hard.
Made the mistake of complicating things for myself and thinking I could defeat gravity and fly rather than taking it easy. Clever me thought it would be a good idea to try and have the images in a grid gallery and the larger image would be in a popup and hopefully navigate from there. Managed to get a popup functioning but couldn’t for the life of me figure out how to turn it into a functioning slideshow, auto or manual. The only solutions were plugins or jQuery galleries like magnific popup.
Before finding the approach I actually wanted with popups I looked into parent windows as a way to enlargen the image in the same window but found it was basically a new smaller tab and wasn’t what I wanted which is demonstrated in my third mockup. Again the window parent/child did work but seemed like a lot of work since I would have to have two to three httml, css and js files. Eventually found a way to successfully open a pop up with a background opacity effect that allowed me to navigate by clicking on the thumbnails to open a larger image.
Reference – (list of research points on various popup, parent-windows, text and hover effects)