I love this picture because of the contrast between the red and the white. It is not a selective color image, meaning that it is black and white and one other color. Instead, Julie's skin is in color, but rendered very pale. Her eyes are their natural tone.
Anyway, I think Julie's expression is incredibly peaceful, a sense made stronger by the fair, pale tones. The red, however, jumps in and provides an intensity to the photo, seemingly at odds with the tranquility of Julie's pose and the tonalities. However, the symbolism of the color red fits for me. It works to make the character of Tranquility deeper, more complex.
This is one of my all time favorite photos.