When we look at a picture our sense organ is active. Our eyes cannot visualize anything without the involvement of our mind. So when we are looking at a picture, we are engaging our mind. As a temporary solution, it is better than having our mind go in 10 different direction. However, ultimately, we want to train our mind to be quiet. Our mind should take instructions from us – which is not happening right now. So this whole exercise is about training the mind.