[Dénes Bernád]

It is only now that I found Clint's private message pointing out this thread.
What he quoted from an earlier statement of mine is still valid. The differences in how various colours can be seen on period b/w photos are greatly pending on what type the original negative was: orthochromatic, or panchromatic.
I attach a sample photo of a Rumanian aircraft, where the marking's colours are well known: the cockade in centre has a blue dot (centre), surrounded by a yellow circle, while the outer circle was red. The cross itself was yellow, while the outline blue. Typical pro-Axis ARR marking.