Interestingly, the Lubavitcher Rebbe was initially opposed to people taking pictures of him. There are several pics of the Rebbe blocking his face from cameras in the 1940s.
At the same time, he spoke strongly of the importance of “tziyur pnei horav” – looking and thinking of a tzaddik’s image as an important method to yiras shamayim.
In later years, he allowed pictures, but even then he only allowed the official photographers, and many times he stopped others from taking pictures, especially bochurim. A relative of mine was once taking a picture of the Rebbe, and he accidently forgot to turn of the flash. The Rebbe confiscated his camera, and later returned it on condition that he would focus on his learning instead of photography.
Rashi says that Yosef overcame his desire to sin when he envisioned the image of his father in his mind (דמות דיוקנו של אביו).
As well as the Gemara that Reb Little Frogie mentioned about looking at a the teacher while learning Torah.
There is also the Gemara in Bava Metziya (84a) how R’ Yochanan would have the women gaze at him when exiting the mikveh so that their children would be beautiful and talmidei chachamim.
There is also the Yerushalmi which Rabbi Hoffman wrote was often quoted by Rav Shneur Kotler that when saying over a teaching of a Rebbe, one should envision him standing before him.
(147 wrote a beautiful suggestion in the comments)