I’d argue that accurate color perception isn’t necessary if one makes an assumption about the average age of the riders. Given that bright hair in humans is either blond or whitened by age (excepting albinos, which are rare), all of the riders having bright hair means that they’re either blond or old. Assuming that there are few large groups of senior riders, Legolas could come to his conclusion based on brightness alone.
Unfortunately I don’t know enough about optics to say whether this makes any difference.
I’d argue that accurate color perception isn’t necessary if one makes an assumption about the average age of the riders. Given that bright hair in humans is either blond or whitened by age (excepting albinos, which are rare), all of the riders having bright hair means that they’re either blond or old. Assuming that there are few large groups of senior riders, Legolas could come to his conclusion based on brightness alone.
Unfortunately I don’t know enough about optics to say whether this makes any difference.
Legolas can also tell that they carry spears and their leader is taller than average. Spectral information is unlikely to tell him that.