I learned the word 'analogue' as meaning something like 'there is a change in the medium in proportion to the signal being recorded'. And digital as 'the signal being recorded is transformed into a numerical value which is stored on the medium'. The consequence being that changes to the medium in the analogue domain (tape wear, attenuation etc) directly affects the signal, whereas in the digital domain the signal can potentially be re-created with no loss of fidelity.

I think chemical film process fits with that description.