I have an image on my website, which I created myself. I have not added any license. The photo is just there.
Google is showing the image in their image search. They also modified it by creating a thumbnail in reduced quality. The thumbnail seems to be stored on their servers.
When you click on the image, Google shows the hint "Images may be subject to copyright."
I know it's possible to write a robots.txt file to forbid Google to show my image. It's also possible to write them a message.
But why is Google allowed to use images without asking for permission? I always thought you need a license or permission to redistribute and modify an image of someone else.
I am registered to the Google Search Console. Maybe I granted them the right to use my image there, but I don't know. I cannot find the image on bing, yahoo or duckduckgo.