When I enter a website, is there a way they would know that I'm using my Adblock filters to block a few images from loading/appearing?
Sure, there are a number of methods that can be used to detect the presence of an Adblock-like extension. Whether a site actually captures that data and logs it is another question.
See this SO question: How to detect Adblock on my website?
Here's a live demo: Adblock Plus detection demonstration
Generally, the technique is to write an invisible element onto the page that you know will be blocked if the user has Adblock installed, such as a JS file with the word "ad" in the title. Then, using jQuery, you can check to see if that element exists in the DOM. If not, then it's being blocked. Based on that result, you could display a message, send a PUT request to your server to log it, and so on.