Colorizing black and white photos

[GuerraCivil]

I have some problem to figure out what colours were used to paint the Legion Condor´s (LC) Bf 109. The expert book like Robert Forsyth´s "Aces of Legion Condor" shows something resembling green olive camo for all colourplates of Bf 109. To my mind this is too dark compared to many black and white photos of the Bf 109 of LC - many of them seem to represent something resembling light grey. Here what one expert has to say about this:

"A further good example of this is provided by the grey upper surface colour used on Condor Legion fighters... 20 years ago, every colour reproduction of Bf109s in Spain showed them bearing a light neutral grey scheme, often called "gull grey". However, recent research, based on contemporary German records and surviving aircraft parts, seems to point to the grey being a much darker, greener hue. In fact many of the fighter aircraft sent to Spain may have been finished in a colour much closer to, if not actually, the famous RLM Grau 02.
Much of this research was incorporated into the recent Jagdwaffe title by Mombeek, Smith & Creek (1999), which caused many reviewers to remark unfavourably on the dark colours they had given to their aircraft. Merrick (2005) expands on this research considerably, suggesting that the earliest Bf 109s were finished in bare metal with a yellowish-greenish-grey protective varnish applied, and that all Bf 109s were repainted in RLM 72 or 73 on the uppersides at some later point.

Of course, trying to reproduce colours on a web page to be viewed on a computer screen adds yet another layer of complexity to the whole question. So I would like to proudly claim that all the colours on my web site are completely and utterly inaccurate!
The difficulties of estimating colours from monochrome photographs are discussed further by Ian Huntley (1994)."

Could it be that the expert historians of LC know with certainty that SOME of Bf 109 in Spain were painted with olive green or green-grey (upper surface), but they just don´t know what may have been the lighter upper surface represented in many b/w photos?