This photo shows a very unusual colour for alpine fireweed. I wonder if the photo was taken in the shade or some other unusual light condition, or possibly using a colour filter?

I thought the same thing to be honest. It looks to be shaded at the very least, but would not be surprised to find out some sort of filtering was also in use here. But the clarity of the picture made me post it anyhow, as much of the blooms detail can be readily made out here much better than a lot of other pictures I've seen of this plant.

Given that the colour of the leaves seems to be affected too - they are usually a light glaucous (bluish) colour, but are very dark-looking in this photo - I'd guess perhaps a filter may have been used.

My guess would be shade, I have had photos turn out with darker foliage and bloom colors when the light conditions were low. It should have been edited but I assume the photographer wanted this more dramatic shot, which is nice.