It's actually the other way around. By making it brighter is appears white. Too busy to find source right now, maybe later.
It is moving away and inside the tunnel, rather than the other way around. The people in the station appear Caucasian so most likely they read from left to right. The writing on the walls and the train is (consciously or not, but probably consciously) placed in such a way that it can be read easier in movement. So if the train moves toward the dark part of the tunnel, those inside it can more easily read from the station's wall and those waiting in the station can more easily read what's written on the sides of the train. Also, at the point where a train is at high speed, where do you think bystanders will look? In the direction the train is moving seems more likely than the direction the train is coming from.
I cant believe people are talking about that dress picture on here as well. Its on every website now and I can't get away from it.
Im pretty sure the dress is either due to colour deficiency or light deficiency. People with perfectly fine eyesight see it as blue or black (75% according to the poll) and people with the slightly off eyesight see it white and gold.
http://www.dailymail.co.uk/news/article-2971409/What-color-dress-White-gold-blue-black.html Ok, found the article. Read it. It explains how adjusting brightness makes it look white and gold. It's an optical illusion and the colors you perceive depend on the colors you perceive on the surrounding objects. But regardless of what you perceived, the fabric was made as blue and black. There is a video with someone explaining and some gifs and all that. Here's a quote: "True colours: The dress, made by the company Roman Originals, is in fact blue and black striped". I'm done with the subject.
The problem with the whole dress thing is that while it's explainable, it's not apparent in the original image that the white balance is SO far out of whack (unlike the xkcd comic's version).
The BBC has claimed the damn thing is Blue/Black and I tend to trust them over Reddit: http://www.bbc.co.uk/news/uk-scotland-highlands-islands-31656935