Thank you Mr.Holmes ,
I thinked this idea with many others when I thinked to think about something is necessary for analog people. Now I am reading Tintins and having great time. Magnetic tape reader idea is really great and digital recording did not reach its quality. I dont know whether silver is magnetic or not but may be other magnetic inorganic crystals would be able to used.
And this film have infinite life. You dont need to buy new film.
And if silver is magnetic , this is a new scanner technology also.
And there is photochromic chemicals also. May be a chemical sensor could be used as a scanner also .
May be someone can bleach the silver and replace it with magnetic pigments to be magnetic scanning.
Or you can tone the print or film with silver halides or others to change the tones with heat or light.
This makes multigrade paper or film.