Just a guess, but it may have something to do with running a gamma correction before and forgetting to reapply it later
If you open the brighter image and run a levels adjustment with the middle slider setting of around .45 then it looks like the darker one. Normal gamma is I think 2.2, and the reciprocal is .45 adjustment
Image about encoding and decoding gamma.
http://blog.johnnovak.net/2016/09/21/wha...out-gamma/
Again, this is just a guess, but it seems quite a coincidence that running a gamma adjustment of around .45 (actually it is .45454545...) makes the lighter one match the darker one.
If you open the brighter image and run a levels adjustment with the middle slider setting of around .45 then it looks like the darker one. Normal gamma is I think 2.2, and the reciprocal is .45 adjustment
Image about encoding and decoding gamma.
http://blog.johnnovak.net/2016/09/21/wha...out-gamma/
Again, this is just a guess, but it seems quite a coincidence that running a gamma adjustment of around .45 (actually it is .45454545...) makes the lighter one match the darker one.