How to Change The Sky in a Picture Using Photoshop

Photoshop is probably the best known image editor around. One of the reasons people use Photoshop is to change elements in their pictures, to ‘improve’ what is already there or swap one thing for another. Replacing a dull sky with a bright one is something Photoshop is perfect for and this tutorial will show you just that – how to change the sky in a picture using Photoshop.

This is the before and after of the image I’m using in this tutorial:

Click the image to see a larger version.

Many Paths – The Photoshop Learning Curve

With Photoshop, there are often several ways of doing something to achieve the same result. This can make the task of learning seem more difficult than it is. Some techniques for changing the sky in a photo are quick and easy, but in my opinion, they are not as convincing. These other techniques involve using:

• Gradients
• Render Clouds filter
• Tools like the Magic Wand
• Colour Range selection panel

I’m going to show you a way to swap skies in your photos using another sky photo and some masks. The technique can be used on most versions of Photoshop, (I’m using CS6) probably back to version 4 or earlier. I’m also working on a Mac, so the keyboard shortcuts for a PC will be different on any screenshots. I’ll mention them where needed.

The sky I’m using comes from a Dreamstime image #122799, but you can use any suitable image, one that is not wildly different from your original photo if you want to get the most natural results. You recolour your photo so the ‘new’ sky sits better, and I’ll be doing that in this tutorial.

How to Change The Sky in a Picture Using Photoshop

1. Once you have your photo, I’m using a picture of a London house, you need to know the size of it. To add a new sky, it will be best to use one that closely matches the image size. This is because changing the size of the new sky photo will possibly add artefacts or create noise/grain that is noticeably different to your photo. To get the image size, go to Image > Image Size. (You can use cmd + alt + i on a Mac or ctrl + alt + i on a PC. This doesn’t work on older versions!)
   My house photo image size is 2315 px (pixels) wide x 1600 px high. The Resolution is 96 Pixels per inch (ppi). The resolution will only really be an issue if you want to make an image larger. My sky photo image is 3008px wide x 2000px high and has a resolution of 300ppi. This means I will be able to reduce the size of my sky image without it being too obvious.
2. Make sure in Photoshop you have your Layers palette showing. If it is not already open, go to the Window menu item and down to Layers.
   Layers are like a stack of paper – whatever is higher is seen first. You can cut holes in your sheets of paper by erasing (permanent) or masking portions (non-permanent and editable.) More on that later.
3. Go to your sky photo and select the Move tool (press V on your keyboard or select it in your tool palette). You are going to drag this layer on top of your house photo, so you need both images open. Hold the Shift key on your keyboard down before you start dragging. This will place it in the middle of your destination photo. If you are using a version of Photoshop that has tabs to arrange your images, you will drag it and hover over the tab until it becomes active, then let go. If you have an old version of Photoshop or prefer to arrange your files in separate floated windows, hold Shift and drag the sky onto the house.
   You will see that the new Layer 1 has a coloured background in the Layers palette. This means it is the active layer and any edits you make will affect this layer. To make life easier later on, let’s name our layer by double-clicking where it says Layer 1 and calling it sky. Let’s also name the house layer by double-clicking the Background layer. This will also unlock it, which means we can move it in our layer stack. Name it ‘house’ then drag this house layer above the sky layer. (Click on the layer icon and drag upwards to move it above the sky layer.)
   Our house layer is now active. We are going to copy this house layer, so either click on the layer and drag it down on to the new layer icon, which looks like a page with a folded corner, or use cmd+j (on a Mac)/ctrl +j (PC) on your keyboard.
   If you add the alt key to this keyboard shortcut you can also instantly rename your layer. Name the copy new sky and click the eyeball icon next to the layer thumbnail to hide the layer. This is what you will have in your Layer panel now:
   
4. We are going to hide the dull gray sky in our original house layer, so select that layer to make it active, then go to the Tools palette and select the Polygonal Lasso tool. Looking at the Tools palette, you will most likely see the regular Lasso tool, with a small triangle next to it. Click on this and hold your mouse key down until the other options appear:
   For this next step, we are going to use the Polygonal Lasso to make a selection. I would suggest that the Pen tool would be better in some cases, but that would need a tutorial in it’s own right, so for simplicity, let’s start clicking on our photo of the house in the main Photoshop canvas/work area. Actually, before you start clicking, a couple of useful keyboard shortcuts: to show the whole image in the canvas, press cmd/ctrl + 0. (Zero not O!) To zoom in and out you can use the cmd/ctrl key along with the +/- keys.
5. Click around the outside of your canvas first, with each click making a new position in your final selection, then go round your foreground (house) content to select it. If you need to make more intricate selections, take your time to click as close to the edge as possible on your house, or at least close enough to not have white or very pale areas of the building left behind. You are only really interested in protecting parts of the house from the blending trick we are going to use soon. Any areas that have been cropped can be tidied-up afterwards; you can edit layer masks which is why they are better to use than cutting sections out permanently. We are doing this as efficiently as possible I hope! When you get back to where you first started clicking, the Polygonal Lasso tool will have a small circle next to the icon and you can let go after clicking. This closes the selection and you will see a ‘marching ants’ selection:
   
6. Making sure your house layer is active, click on the Layer Mask icon at the bottom of the Layers panel:
   You will immediately see your sky layer appear below this hidden (masked) area in your house layer. At this stage, you might want to resize or reposition your sky layer, so select it and hit cmd/ctrl + t to bring up the Free Transform options.
   Tip: if you don’t see the surrounding box and control handles, use cmd/ctrl+0 to zoom out to show them all.
   
7. Click the visibility eyeball on the new sky layer to show it, and click the layer to make it active. We are going to blend away the sky using the layer Blending Options. You can access these by using the small triangle at the top-right of the Layers panel, or by double-clicking in a section of the layer next to the ‘new sky’ layer name. It will open a large panel with Layer Style across the top. We want to change the Blend If drop menu to Blue (rather than Gray) and click and drag the slider arrows on the right over to the left, on the top (This Layer) slider.
   
8. We are using the Blue option as our sky has little or no Red or Green colour information in it. At least it shouldn’t have… Skies tend to be blue so we can target that colour channel and as you start dragging to the left, you will immediately see the sky start to appear below. Our house layer with a mask below protects sections of our building being blended away. Drag the twin slider arrows (yup – it’s actually two blend points) to the left until most of your sky is hidden, but other elements like leaves are not lost along the way:
   
9. Hold down the alt key on your keyboard and click on the blend slider to split it, dragging half of the slider to the right. This will soften the blend transition. You will see the results of this best if you have zoomed in (cmd/ctrl +) on your image.
   
10. Click OK and you are done!

Wait! Does your original house image layer look too washed-out in comparison to your lovely bright blue sky? Bright skies mean brighter colours, so you may need to give a bit more Saturated colour to your house layer to blend it more convincingly.

Depending on your version of Photoshop, there are different ways to approach this. At the most basic level, hide the visibility on the new sky layer then select the image icon your house layer (rather than the mask icon – it will have a square around it indicating what is selected). Go up to the Image menu and select Adjustments. Use the middle (Saturation) slider and move it to the right to add between +10  and +20 more saturation to the colour. You will have to use your eye and your own judgement on this one!

Make a note of the number you increased it by then switch on and select the new sky layer. Apply the same amount of Saturation to this layer. You may also need to revisit #8 above to tweak the Blue Blend If slider settings.

This method applied the increases in saturation permanently to your layers. A better option is to use Adjustment Layers to apply non-destructive changes. Better still, if your version of Photoshop allows you to create Layer Groups (or Sets in older versions), select both the new sky and house layers by clicking one then the other while holding the Shift key. You can then use cmd/ctrl + g to group the layers, use the New Group from Layers… option in the layer menu flyout, or go to Layer > Group Layers. This basically creates folders for organising your layers, but you can also apply Adjustments to Groups.

1. Add a new Adjustment Layer to the Group, by either going to Layer > New Adjustment Layer > Hue/Saturation… or by clicking the icon at the bottom of the Layers palette. (It’s a circle, half-filled with a small arrow next to it where you can select Hue/Saturation…)
2. Make sure this new adjustment layer is at the top of your layer stack by dragging it in to place if you need to. Move your cursor so it hovers between this layer and the layer group, and hold down the alt key. You will see the cursor change:
   This means that our Hue/Saturation changes will only affect the layers in the group and not the sky layer. You can see the layers below our Adjustment Layer are indented and there is an arrow pointing down to our Group 1 layer. The layer name also becomes underlined showing us it is part of a new ‘clipping group’.
3. Finally, I have added a Curves Adjustment Layer to my whole image to give it some punch!
   

Here is the before and after again, below. Click to enlarge:

house before

house after

So now you know how to change the sky in a picture using Photoshop! There are many more retouching tools available and techniques that can improve your photos, so if you are interested in learning Photoshop with some 1-2-1 training, find out more here.

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