It's very obviously (to those who do post-production processing) a matter of exposure settings and then shadow enhancement using software such as Gimp, Fast Stone, PhotoShop, Lightroom, or Affinity. The first image of the Northern is indeed underexposed, and then the slides in shadow adustment are moved to the right.
For their builder's photos the PRR used a low-reflectivity gray paint and they even white-washed the headlight and cab glass.
PRR_Q2 by Edmund, on Flickr
Regards, Ed
gmpullmanand they even white-washed the headlight and cab glass.
The headlight and cab windows in that PRR picture look like ordinary photo retouching of the period to me. There's some other detail and highlighting that loks like it got the treatment, too...
OvermodEd, did they actually do that?
Based on dozens of PRR photos of special-built locomotives coming out of Juniata Shop I would say yes. In order to confirm this I'll have to pose the question at the PRR IO list. I have seen some high-end brass models painted in the "photo-gray" paint and I seem to recall Al Stauffer mentioning the whitewash (maybe it was white shoe polish?) painted over all the glass surfaces, including the lenses of the pilot-mounted markers and class lights.
https://digital.hagley.org/PRR_11050
Because Lionel tried pink, and it went over about as well as a Lead Zepplin.
Just for ,
PMR