Night on the town
1 Mask the sky
Open day_night_before then grab the Quick Selection tool. Paint to select the sky. Next click the ‘Select and Mask’ button at the top, then set Radius 4 and paint with the Refine Edge brush over any tricky edges. Once done click ‘Invert’, set Output: Layer Mask and hit OK.
3 Drop in the stars
Open day_night_stars and use the Move tool to drag the image up to the tab of the main image, then down and in to copy the image over. Go to the Layers panel and drag the layer to the bottom of the stack then position it over the sky. Hit Cmd/Ctrl+T to transform the layer to fit.
5 Glowing windows
Grab the Polygonal Lasso tool and select the windows. Next add a Solid Color adjustment layer and choose a bright yellow. Double-click the adjustment layer to open its Layer Style menu. Click ‘Outer Glow’, choose an orange tone, set Mode: Linear Light and set sliders as above.
2 Remove the people
Click the New Layer icon in the Layers panel then grab the Spot Healing Brush tool and check ‘Sample All Layers’ in the Tool Options. Paint over the people to remove them. If necessary, switch to the Clone tool and use it to tidy any rough patches.
4 Adjust the tones
Highlight the top layer then click the Create Adjustment Layer icon and choose Color Balance. Push the sliders towards cyan and blue then experiment with the Highlight and Shadow settings. Next hold Alt and drag the layer mask thumbnail to the newly created adjustment layer.
6 Final adjustments
Next press Cmd/Ctrl+Shift+Alt+E to merge a layer at the top of the stack then go to Filter>Camera Raw Filter for final tonal adjustments. Reduce Temperature and Saturation as shown, and experiment with Exposure until it looks right. When you’re happy, hit OK to apply.