Can you access the broadcaster's video stream?

Hi I am a new Twitch developer and looking to build a image analysis on streamer’s video and find color and obj, which then apply a theme to viewer’s video overlay.
As you mentioned,

You could create a module that integrated with a broadcaster’s stream prior to ingest

Do you have any pointer? or examples? of how this can be achieved? Since others are using such a functionality, I assume this is available to public?

Thanks in advance.