How to transform a brightly lit shot into an atmospheric nighttime scene
Start by opening your image. The first thing we need to do is lighten the image up slightly by using the Levels adjustment (Layer>New Adjustment Layer>Levels). Move the middle slider to the left.
Cameras work by seeing artificial light as orange and the natural light as blue or dark blue: we can replicate this effect by using a Hue/Saturation adjustment layer. Add the adjustment layer via Layer>New Adjustment Layer>Hue/Saturation.
First we want to tick the Colorize box at the bottom of the adjustment layer then move the Hue slider to 205. Move the Saturation slider until it reads 33 and the Lightness slider so it reads -40. Change the Hue/Saturation layer’s blend mode to Multiply. This darkens the image and makes it looks like it was taken at night.
Either find a stock image of some stars or add a black layer, and go to Filter>Noise>Add Noise. Then go to the Filter Gallery and choose Photocopy. This will create a starry effect. Hide both this and the adjustment layers.
Select the Magic Wand tool and, in the Options bar, click the Add To Selection icon, untick Contiguous and set Tolerance to 15. Move back to the first layer and start to click the sky. Keep clicking until all the blue is selected.
We now want to add a Reveal Selection layer mask (Layer>Layer Mask>Reveal Selection). Unhide the Stars and adjustment layers.
Create a new layer at the top of your stack called Lights and set your Foreground colour to to a light blue(blue). Select a soft edge brush and paint in light, using an eraser or a layer mask if you go over the edges.
Set the Lights’ blend mode to Overlay and duplicate it. Reduce the Opacity to 70%. Repeat these steps for anything else that needs to be lit up.