If you run python app.py this API will be launched and hitting to http://localhost:7000/img/my_image.png is going to show your my_image.png image in the img folder.
Now insert the link of your image (starting by http://localhost:7000/img/...) in your utterances in your domain.yml file and all your images should show up in your interface in Rasa X
PS : you are free to change ports, folder names, etc…
The above solution what you said will be good for rasa x ui,how can i handle this with custom ui,i mean rasax ui directly load image but custom ui not, how can we display the image in custom ui.
and also can you tell me how to integrate rasa with custom userinterface