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Sky replacement in Affinity Photo – transform day to night!

Watch video: Sky replacement in Affinity Photo

Like Photoshop, one of the biggest benefits of using Affinity Photo is the layers feature. Layers enable you to combine a range of images and effects to completely transform the look of your photos. We can even change day to night. In this tutorial we’ll look at how this is done with a simple combination of layer skills. 

Read more: Affinity Photo 1.8 review (opens in new tab)

We’ll begin by making a tonal adjustment to transform the bright blue sky into a moody nighttime backdrop, altering the colors to cool things down and darkening the midtones to plunge our subject into darkness. We’ll use the Gradient Map tool for this, which enables us to map a range of nighttime shades onto the tonal range of our image. 

The Gradient Map adjustment in Affinity Photo enables you to remap colors onto different parts of the tonal range. Here it sees us add a dark blue tone into the shadows and midtones, thereby transforming the bright sunny day into a scene that looks as if it was actually shot on an atmospheric night. By default the gradient map enables you to add a blend of three colors, but you can double-click the line to add more if you choose (and hit Delete to remove colors, if you need to).

Click to download the project files (opens in new tab) (Image credit: James Paterson / Digital Camera World)

It helps here that the original photo is shot in hard sunlight as, with the colors altered, we can make the sunlight look almost like moonlight instead, which has a similarly hard-edged quality. 

To finish things off, we’ll drop in an image of a starry sky, then fit it into the backdrop, thereby transforming the blue backdrop into a star-filled evening scene. This is done by first selecting the blue sky with the Flood Selection tool, then converting the selection to a layer mask in order to constrain the stars to the area of sky on the layer below. 

An ability to combine photos with layer masks like this is one of the cornerstones of image editing in Affinity. Master these skills and you can merge all kinds of photos and selective effects for endlessly creative results.

1. Add a Gradient Map

(Image credit: James Paterson / Digital Camera World)

Open day_night_before into Affinity Photo. Make sure you’re in the Photo Persona (top-left purple icon) then go to the Layers panel (Go to View>Studio>Layers if it’s not on-screen). Click the Adjustment Layer icon at the bottom of the Layers panel and choose Gradient Map.

2. Darken the midtones

(Image credit: James Paterson / Digital Camera World)

Click the circle on the left of the line. This enables us to change the colors of the shadows. Click the color box and choose a dark blue tone for the shadows – here we’ve used H 213, S 100, L 7. Next, click on the middle circle and use a slightly lighter blue for the midtones – we had H 202, S 57, L 8 here.

3. Alter the gradient

(Image credit: James Paterson / Digital Camera World)

Add another color on the gradient map for the highlights – we used a light purple (H 292, S 23, L 57). You can also double-click on parts of the line to add further spots of color to the blend, just like we’ve done here with a few extra spots in the shadows and highlights of the image.

4. Select the sky

(Image credit: James Paterson / Digital Camera World)

Open day_night_stars. Hit Cmd/Ctrl+C to copy then go to the other image and Cmd/Ctrl+V to paste. Click the ticks next to the top two layers to hide them and highlight the bottom layer. Grab the Flood Select tool and click over the sky. Hold Shift and continue clicking to select all parts of the blue sky.

5. Mask the stars

(Image credit: James Paterson / Digital Camera World)

Click the Refine button at the top to improve the selection. Increase Border Width to 30% and hit OK. Next, reveal the other layers and highlight the top layer, then click the Layer Mask icon at the bottom of the Layers panel to change the selection to a layer mask. Hit Cmd/Ctrl+D to deselect.

6. Blend and tone

(Image credit: James Paterson / Digital Camera World)

Go to the Layers panel and change the blend mode of the stars layer to Screen, then lower the layer opacity to around 75%. Finally, click the Adjustment Layer icon and choose Curves. Drag the top-right point on the line downwards to dull the highlights slightly, as shown.

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About N-Photo magazine

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The lead technique writer on Digital Camera Magazine (opens in new tab)PhotoPlus: The Canon Magazine (opens in new tab) and N-Photo: The Nikon Magazine (opens in new tab), James is a fantastic general practice photographer with an enviable array of skills across every genre of photography. 

Whether it's flash photography techniques like stroboscopic portraits, astrophotography projects like photographing the Northern Lights, or turning sound into art by making paint dance on a set of speakers, James' tutorials and projects are as creative as they are enjoyable. 

As the editor of Practical Photoshop magazine, he's also a wizard at the dark arts of Photoshop, Lightroom and Affinity, and is capable of some genuine black magic in the digital darkroom, making him one of the leading authorities on photo editing software and techniques.