Meine Herren !
Deducing colours from b/w is possible but does not come easy.
A b/w material translates colour rays into grey tones.
Ortho- or Panchromatic material does show a given colour in a given grey tone/hue.
The significant influences on this tone are shutter speed, lighting conditions, development conditions for film and(!) paper copy
and the use of optical filters to influence they grey tone / enhance a certain grey tone etc.(they could be used during the developing process, too!!)
So just deducing from the panchromatic (1906) material would be easy; you just have to find out how this material usually rendered colour.
Then one may say: this was a yellow tone.
But you still will not know, what yellow hue.
Therefore one has to gather knowledge on the then used paints etc.
The filters/lighting condition / shutter speed - influence is a hard nut to crack; it severley changes the defined panchromatic
grey tone.
In the end one may get close and it is a real scientific work and worth it, but does not come easy.
The computerized colouring of b/w-films ("WW I in Colour") is just nice.
Very correct indeed was the Autochrome Process, delivering very good colour representations, maybe even better, than Kodachrome 64 or AGFAchrome.
Imagine: real colour photography, not b/w photos painted afterwards with albumin transparent varnish paint !
I think no one really has researched how many WW I autochromes survived on military items.
As a tit-bit I recommend the BBC series -available in print and DVD on the French Banker Kahn ( who wanted to do a complete photostory of the whole world in autochrome colour); at least some WW I frames are shown!
viele Grüße, Gunther