1) This is not Stack Overflow.
2) This is your homework: We don't do it for you: it is set for a reason. It is there so that you think about what you have been told, and try to understand it. It is also there so that your tutor can identify areas where you are weak, and focus more attention on remedial action.
If you meet a specific problem, then please ask about that and we will do our best to help. But we aren't going to do it all for you!
3) I wouldn't try to do it via an app - I'd look into a Chrome extension first as that can access urls / images that are opened a lot more easily - you then just have to find a way for that to communicate with your app.
Getting Started: Building a Chrome Extension - Google Chrome[
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