One of my favorite Film Theory professors faced us often with a question: how would you describe this alien movie without mentioning aliens? I was astounded by that question because it helped me appreciate the science fiction genre more and actually made them interesting.
I think that is the reason I admire Arrival so much, because when I form the answer to that question for Arrival, the topic seems very thrilling and exciting to me.
Arrival is a presentation of how we choose to perceive time and memories and how language serves as a complex tool full of vagueness.
Have a better one? Comment down below! I always enjoy reading others' answers to this question.
The fact that the aliens have been talked to instead of chased or fought leaves this particular memory of Arrival in my mind after I am done watching it. The aura and mysterious approach to the heptapods is so special that I catch myself recalling that they are not real. (Or are they?) Whenever I contemplate Arrival, I can't recall the exact look of them. It's because of how differently shaped they chose to create them, and the fact that they are so still in their fogged space behind the glass. It seems to me like whenever I revisit Arrival, I go back to that platform myself to meet the creatures for the first time.
Darkness in the frame seems to refer to the emotional dullness that accompanies Louise on a daily basis. The flashback sequence at the beginning of the film sets up the connotation between Louise's past full of dramatic events and her present life that does not receive more brightness after the flashback sequence ends.
It does not mean there is no light or daylight in the flashback sequence, however in each element of the montage the characters' faces are not shrouded in that light. The cinematographer uses mostly back light to embody the memory of Louise's daughter. In the one exterior part of the montage there is more light filling the scene, but, even though it seems like the action is playful, we do not trust that their reality was mostly joyful because of the overcast weather mood in those shots. Incorporating this one exterior into the sequence helped it avoid monotony (by being overly dramatic and therefore bombast). Also, shooting it during melancholic overcast weather makes it more believable than using only interiors shot in the studio.
Why is setting up the darkness so important for this film? The brightness level management in Arrival seems to have a particular purpose: to contrast most of the film with the culminating action when Louise enters the White Space of the heptapods. The blinding white brightness is clearly the symbol of the aliens' presence in the film. We can experience the introduction of that blinding bright light during Louise's first encounter with them.
As you can see in the breakdown, the ratio of the brightness to darkness in each frame during most of the film is opposite to that ratio when Louise is in the White Space.
I am a huge fan of this particular engagement of cinematography and color grading because it incorporates a visual effect to work on our physiological response when the action of the film calls for such reaction. Having our eyes so used to the low highlights in each frame for about 1 hour and 26 minutes will cause sudden brightness to shock our pupils. Therefore, what we experience emotionally accompanying Louise in the White Space, we also experience physiologically by being somehow blinded with the amount of light our eyes are now exposed to.