Can I prevent previews of images in Finder?
Yes you can disable the image previews on Finder.

Right-click on the folder and select "Show View Options."

A long window will appear. On the 5th group from the top, you should see a checkmark called "Show icon preview". Deselect it.



Once you are done, select the "Use as Defaults" bottom, which is located at the bottom of the window.