ah yeah the images are stacked on top of each other so doing an opacity would be challenging here. I would say your best bet is to wrap the image in a div, and match the background color of that wrapper div to the background of the section, and then you can try changing the opacity. However I noticed you have a lot more images than you do have sections and I noticed that the is-image1 and is-image2 combo classes were duplicated - so I would first make sure that is all cleaned up so its not so confusing.
The other thing you might have to do is essentially copy/paste the profiles_image class and move that up as your new wrapper class potentially - I noticed when I tested this, it changed the aspect ratio of the image so you'll want that new wrapper div to have the same settings that the current image element has and then make adjustments from there like renaming the actual image element to something else.
If I've lost you, just let me know and I can do a quick loom on it later this evening.
