faster navigation: what's the best/easyest option?

[sirtet]

I gravitate towards a slider, like a video-player timeline.
would use less UI space.

Maybe a classical gallery (row of thumbnail pictures) would be quicker to implement?
maybe downside: you can only directly tap a few images, or they would become extremely small.
@tim-lloyd, you favour a gallery, can u provide a link to an example on what you mean by that?

[tim-lloyd]

The main point would to be able to move through the current images quickly to get a sense of how the level is varying.

I suggested a carousel for example
https://getbootstrap.com/docs/4.0/components/carousel/#example
I assume there are many libraries to do this. Also there will be other ideas like the slider you suggest.

To be clear, I am talking about the current images, not for the reference pictures. I think reference pictures should be few and curated.

[sirtet]

there's many examples there... which exactly?
PS: the slide EFFECT is out of question, it will be immediate replacement, but i guess that's clear...

[tim-lloyd]

None exactly. It was a conceptual suggestion.