Sky-high selection skills
Make complex cutouts with ease using Channels in Photoshop CC, and replace a dull sky in minutes
As far as cutouts go, it doesn’t get much more daunting than this. The Eiffel Tower is about as complex a shape as you can imagine. The iconic outline is simple, but it’s all the little gaps and spaces in between that pose a challenge for anyone wishing to make a selection. The bare tree branches on the right of this particular photo make things even harder. So how can you cut out an object like this?
You can forget using the freehand or simple selection tools: it would probably take a week. Even the Quick Selection Tool or the Magic Wand are likely to struggle. Instead, you can use the information in the image itself...
The key attribute of this shot is that the dark shapes of the building and tree are clearly defined against the brighter sky. This is all the information you need to make a complex cutout in seconds. Photoshop Channels allow you to break an image down into separate components based on brightness and colour. All you have to do is pick the channel that gives you the greatest contrast between the subject and background, then duplicate it and alter it so that one part is completely black, the other completely white. This gives you the selection you need to manipulate the photo further.
After making my complex selection, I’ve dropped in a new sky to add a little impact to this Parisian scene.
1 Copy a channel
Open the start image eiffel_before.jpg, then go to Window > Channels. In the Channels Panel, click through the red, green and blue channels and assess which one gives the most contrast between the object and surroundings. Drag this channel to the New Channel icon at the bottom to copy it.
2 Increase the contrast
Next, go to Image > Adjustment > Levels (or press Ctrl/Cmd+L). In the Levels box, drag in the black and white points to increase contrast. The objective here is to make one part completely black, the other completely white. However, don’t push things too far yet.
3 Paint black and white
Grab the Brush Tool from the Tools Panel. Go to the tool options; set the Brush Mode to Overlay and Opacity to 50%. Press D to set the colours to white and black. Paint the background to make parts white, and switch to black to paint over the foreground details until they’re black.
4 Convert to a mask
When you’re satisfied, hold Ctrl/Cmd and click on it to load the white parts as a selection. Next, click on the RGB channel then go to the Layers Panel. Click the Add Layer Mask icon to convert the selection to a mask. Press Ctrl/Cmd+I to invert the mask and hide the sky.
5 Drop in a sky
Open the start image eiffel_sky.jpg in Photoshop. Grab the Move Tool, then drag the image up to the tab of the cutout image to copy it over. In the Layers Panel, drag the cutout layer above the sky layer. If you need to resize the sky to fit the image, press Ctrl/Cmd+T to enter Transform Mode, then drag the box.
6 Enhance the tones
Alt-click the Layer Mask thumbnail to view the mask. Fine-tune the mask with the Brush Tool in Overlay mode until it’s perfect. Finally, add a tonal change: click the Create Adjustment Layer icon in the Layers Panel and choose Color Lookup. Click 3DLUT and add the FallColors preset.