In fact, the AlNiCo magnet was one of the strongest until recent advances in materials science passed it up. I don't know what the leader is now.
Under very high magnetic force, it has been demonstrated that most objects are magnetic. In fact, a recent demo on TV showed a spider suspended in a chamber, in mid air, by a huge magnetic field.
The electromagnetic forces allow electrons to create magnetic fields and magnetic fields create electricity. This has been known for hundreds of years, and was demonstrated by Benjamin Franklin among others. These fields can influence radiation, but they cannot influence light. Gravity can influence light, but there is no electrogravitic force or magnetogravitic force (as once was thought) that can combine all 3 forces and allow control over light, magnetiism and electricity.
Put "Faraday Effect" into Wikipedia, and go from there.
It's been known almost as long as photography.
Not the easiest way to modulate an image, I think ...
Using the Faraday Effect, you might have some interaction between magnetism and light, but not with the emulsion itself. Generally, except for a few carefully controlled situations, magnetism does not influence chemical reactions. But, why don't you try it yourself?
You could also try the Surface Magneto-Optical Kerr Effect - otherwise known as SMOKE -
but you might also need some MIRRORS...