FireFox plugin - how to transfer the image displayed on the page to a remote server?

Question

Mozilla Firefox

The plugin is designed for a specific site that periodically asks you to enter a captcha. The plugin should send this captcha to the remote server (mine) and enter the response received from the server. The plugin is used to mask requests to a remote server - it will be more difficult for site owners to trace such a decision.
Everything is more or less clear except how to transfer the captcha to my server?

Answer 1

I found a solution - the image is added to the canvas, how to save it later: https://developer.mozilla.org/en-US/Add-ons/Code_s...

Answer 2

I don’t know how it is in FF, but for Chrome applications there is an api for taking a snapshot of the current site https://developer.chrome.com/extensions/examples/a...