Is this hair diffusion?

[Sprintz]

Hi all,

My hair looks thin (scalp visible) under camera flash or facing direct sunlight. I took a series of pics outside today showing the difference between facing towards away from the sun.

My question: is it normal to be able to see that much scalp, or is this a sign of diffusion and something I should be treating? I'm a 24 y.o. with short hair (1.5 inches or so).

Thanks!

Album: http://imgur.com/a/FS5eB