Decoding old photos

Part of being a historical represntational artist is "reading" old black-and-white photos . "Black" on car sides or locomotives often denotes red . "Gray" is often green . "Off-white" is often yellow (or possibly light green).
This I divine from known practices and conjectures of rail historians .Some is guess work . I know that a lot of locomotive cabs and box headlights on the South Park and other roads like the Silverton Railroad had dark red (maybe burgundy)cabs and headlights . Lots of engines had polished jackets of russia iron , and that is betrayed by a middle gray . As it had been discussed here years before , russia iron was mosto often gun-metal blue-gray , but also was green and copper-red .