I want to use the image labeling python tool "LabelImg" in a browser with angular as front-end. Is it possible to do that?. If no , then how can labeling an image is done using angular so that the pixel values selected for each box in that image is set to back-end?
It is possible. You need to create an api that you can send the image to the python backend and return the result after the python has finished processing the image.
Depending on the python algorithm runtime, you might need to make this task async which would ned more engineering: an api each for sending an image, checking for the labeling status, getting labeling result as well as a storage solution to store the image labeling status and result.
In layman terms, angular frontend and python backend are not coupled together. Angular gives you an interface to communicate to the end-user while the backend api's create a channel to communicate with the python service