If you know the exact position and direction of a photon coming out of the accretion disk, you could theoretically reverse out a trajectory and calculate what d

If you know the exact position and direction of a photon coming out of the accretion disk, you could theoretically reverse out a trajectory and calculate what direction it approached the black hole from at what time. Of course, that relies on incredibly high resolution images and knowledge of the black hole, but it's not impossible.