How is this red/blue effect created?
How do I achieve this effect in colours. I've seen similar effect on Halsey cover art as well. Proficient in CC so hopefully it shouldn't be too hard, just thought I'd ask here first.
This is very likely a gradient map, which allows you to map different colors to the luminosity of a given picture.
There's more than one way to apply a gradient map:
Select the desired layer, then go to Image â†’ Adjustments â†’ Gradient maps. This is destructive.
In your layer palette, click the Fill and adjustments button and select Gradient map. This will create an adjustment layer, which you can put on top of the layers you want to affect. It can also receive a mask to control its effect. This is what I do in the following steps:
Then, I applied a gradient map that gives a rich red to the darks, tapers off to the grayish magenta you see on lighted columns, and I isolated part of the highlights range to get the blue-green. Absolute whites go back to a light magenta tint.
Note that the original picture probably had "real" whites, which were then mapped to a slight gray. This would make it hard to recover the right luminosity for the sake of this demo. Here's how I defined my gradient map:
The leftmost colours will replace the blacks, the rightmost will replace the whites.
Here's the result with the gradient map applied at around 50% on my quickly grayed-out source:
Keep in mind that ideally, you also do some manual adjustments in the end.