When shooting outdoors, say if I do get legal permission to use, say a parking lot for example. The public sidewalks in the background will still be free to use for whoever wants to walk by. I need to make these people unrecognizable since I do not have their permission from them to be in the movie. Can I use blur on them and then it would just come off to the viewer as a shallow depth of field or is that not good enough? I'm not only asking legal wise, but also style wise, if the blur is acceptable? Thanks.