Images and page content themselves aren't captured, just the loading of them if that's what you want to stop. Assuming you're talking about things at the RUM level what exactly would you even be capturing if you were able to turn that off?
There's no method I'm aware of to completely stop gathering data about web page and image loads.
Probably want to expand on what exactly you're trying to prevent.
In dynatrace appmon if I want to exclude certain URI's or images I can add that rule by going into servlet sensor or web request sensor.Similarly how can i exclude in dynatrace.