Damien Van Der Cruyssen (colorist): I asked the crew to shoot film on a dark gray background. We pushed that negative, like the rest of the film footage. We had 30-second samples at pushed 2 stops, pushed 1 stop and normal. Most of the grain we used was pushed 1 stop. I created a loop with two minutes of grain to add to the Alexa footage… Yes, the grain is a black and white image, but I can also tint this grain overlay. On some scenes I made the shadows a little cooler. We varied the grain to match the image. I can push that slider and adjust the amount of grain. Sometimes I pushed the contrast of the grain also. We didn’t want it to feel like the same grain overlaid throughout the movie, each scene has its little differences.
Darius Khondji: Remember that I pushed the film negative one or two stops to bring out the natural grain. At the same time, I push 2 stops but I only expose for 1 stop, so I clean up the negative before I put it in the bath where I add 2 stops. I augment the contrast and the grain, so that the grain exists but it’s not too noisy.
Benjamin B: If the bokeh is the personality of the lens, then maybe the grain is the personality of the negative. But it's strange that you can add that personality to your digital images. It's like putting the ghost of the negative into the Alexa images.
Darius Khondji: Extreme beauty is always right next to uglyness.
The whole article is a fascinating look into a collaboration between a DP and a colorist to achieve artistic looks.