Impact of search of images on log for SEO

I recently stated a huge difference between the traffic monitored in the Search Console and what I could find in the log files using Kelogs log analyzer. My first hypothesis is that Google Image could be at the origin of this difference, with a preload in background. Second hypothesis is that the first results in Google Web is preloaded if the page is usually too slow.

Protocol to check the first hypothesis:

I’ll try to get the image below indexed for this website, despite it is hosted on amazon, and I will live check the impact on log files when I search for it in Google.

Let’s come back in few days when Googlebot will have indexed this page and display the image in Google Image (I’ll use “site:quentinadt.com” to check it).

So here is the picture of someone swimming:

To check the second hypothesis, Ill make a page which is very slow but ranks on a specific unique keyword.