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A Quick Guide to Replacing Skies in Photoshop


It's great when we have bright blue skies in the background of our photos, but grey days are inevitable. Today we are going to learn a simple technique to replace the skies in Photoshop.

Choosing the right image

The great thing about this technique is that you can do it using any image, although it's much easier with a single-coloured sky.

The main thing to watch out for is reflections in glass, puddles and other shiny surfaces. If you change the sky to a blue shade with some clouds, but the reflections remain a dull grey, your manipulation will look obvious.

For this tutorial, I am using this image of a libary in Bangalore. You can download the image from here. Credits go to the revati_me, the original photographer. Below is the result before and after.

Step 1 - Picking your sky

First of all we need to find a suitable background. I have personally have build up a collection of sky photography I shoot while out and about. My sky photo library is now big enough that I can always find a good replacement.

For the use of this tutorial, I deciced on using another stock image. You can download the clouds from here, credits go to Rolve. You'll need to resize your sky image to fit your scene.

Step 2 - The magic wand tool

Hide the sky layer for the next step. Because my sky is all the same colour, I deciced that the magic wand tool would work well here. I selected the whole of the current sky section and then created a new layer and filled the selection with a solid colour.

If your photo has clouds or cannot be selected in one go then don't worry. We can use different tools instead. Skip to step 4 and then select the main sky instead.

Quick Tip: The magic wand tool has a tolerence to what colours it picks up. You can increase or decrease this by changing the number at the top when the tool is selected.

The tolerence for the image below was only 8. Other images I have tried needed at least 50 in order to work well.

Step 3 - Clipping mask.

Place your sky layer above the solid fill layer. Then go to Layer > Create Clipping Mask or use the shortcut CMD/CTRL, Shift + G. This will place your sky layer inside of the solid fill layer. Move it until you are happy with the postioning.

You might need to refine the edges as the magic wand over creates quite sharp edges. Simply select the solid fill layer and then hold down CMD/CTRL and click on the layer preview.

This should select the outline of the shape. With the marquee tool selected, right click and then select refine edges. Use the tools to soften the edges slightly.

Step 4 - Fill in the gaps

To begin with simply create a duplicate sky layer, then hide it. In this step we are going to fill in the gaps that the magic wand tool was unable to select. In this photo we have gaps between the trees on the left and right hand side.

With the main photo selected go Select > Colour Range. Use the Eyedropper tool to select the colour in the gaps. In this case it was a light white/grey colour. Move the fuzziness slider until a good selection is covered. A good thing to do at this point is to go to the selection preview and select quick mask. This will give you a better preview of the areas selected.

Step 5 - Layer mask

When you hit OK, large areas of your image will be selected. Make sure you don't deselect them or your will have to restart.

Select the duplicated sky layer. Then at the bottom of the layers panel, you will find a small sqaure box with a circle inside. This button is the add layer mask tool. This works similar to the clipping mask layer. It will show the areas of the cloud layer through the mask.

Below is a image of my layers panel, yours should look similar.

Step 6 - Tidy the image up

The vector mask will have selected everything you selected in your colour range selection. So select the layer mask and then use a black brush to paint over the areas you don't want in the image. If you want to replace areas simply change the colour to white.

These areas were often on roof tiles and around the edges of the building. You might not notice the changes on this small image below but they make a big difference on the larger version.

Step 7 - Check for mistakes

Study the image for at least a minute to see if you have missed a reflection anywhere. Like I mentioned before common places include sunglasses, glass panels and puddles.

In this image there are very few places for reflections. In the places that could reflect I have painted them using a soft blue brush and then set the layer mode to overlay at 25% opacity.

Step 8 - Add any final adjustments.

Finish off by adding any final adjustments such as sharpening the final image or adding a curves layer. In the image below I created a new layer, applied the image and then used the high pass filter. I then set this to overlay and reduced the opacity to around 40%. This just sharpened the image and brought out the colour a little more.

Other examples-

I made this image while I was in Hong Kong. It was horrid day with a dull grey sky. In this image I used the magic wand tool but I had the crank the tolerence up to around 50%. I also had to paint a small amount of the clipping mask myself.

I made sure that the shiny buildings reflected a nice blue colour as well as clouds rather than just the dull grey colour. I also added a brightness and contrast layer at the end to brighten my original image.

Notice the delibrate mistakes? The clouds are wispy and don't match the same shutter speed that the water was shot at. You can have 10 points if you noticed.

Post your results using this technique or others like it! If you have any other tips to share please don't be afraid to post them.

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