How to Replace an unwanted sky
1 Combine two images
Use File > Open to browse to a shot that needs the sky replacing. Choose Select > All, then Edit > Copy. Open a photo with a more spectacular sky. Choose Edit > Paste to put both shots into separate layers in the same document.
2 Choose selection tool
Switch to the Flood Select tool. Using a tolerance of 30 helps to select the church, while ticking the Contiguous box ensures only connected black pixels will be selected. Click in the photo to make a selection. A marquee will appear.
3 Create a layer mask
Choose Layer > New Mask layer. This attaches a black and white mask. You can see a thumbnail of it in the Layers panel. The mask’s white sections keep the selected pixels visible. The black parts make the rest of the layer transparent.
4 Modify the mask
Use ç+D to deselect the marquee. Some of the original ocean is visible. Use the Rectangular marquee tool to draw a selection over the unwanted section. Choose Edit > Fill. Set the custom colour to black. Click Apply to hide the selection.
5 Blur the mask
å-click on the layer mask’s thumbnail to see its black and white pixels. Choose Filter > Blur > Gaussian Blur. Set Radius to 0.6. This blurs the edges of the mask, which helps make the subject look less ‘cut-out’.
6 Copy the sun
Click on the Background layer’s thumbnail, then switch to the Elliptical marquee tool. Hold ß and drag to draw a circular selection around the sun and clouds. Press ç+J to copy the sun selection to a new layer.
7 Enlarge the sun D
Press to deselect the marquee. Click on the copied sun layer. Switch to the Move tool, then drag a corner handle to increase the size of the sun. Go to Edit > Layer > New Mask Layer. A layer mask will attach itself to the sun layer.
8 Blend the sun
Switch to the Paint Brush tool. Click on the copied sun layer’s mask thumbnail to target it, then open the Colour panel. Make sure the primary colour is black. On the mask, spray over the edge of the cut-out sun layer to hide its pixels.
9 Fine-tune the blend X
Black strokes hide the pixels on the copied sun layer. Press to toggle to a white colour if you need to restore any pixels you’ve hidden. This non-destructive editing helps you blend the enlarged sun with the clouds on the layer below.