| How to cheat at Photoshop and not get caught! |
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| Replacing a Sky |
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We often have a landscape picture with a bland sky which we would like to replace. The obvious way in Photoshop is to add a new sky as the background layer, select the old sky in the top layer and delete it, replacing it with the new one. In practice this seldom works in a convincing manner. The top of the hills always looks unnaturally bright against the darker sky and gives away the fact that the sky has been replaced. After much experimentation I discovered this method, which seems to work well every time.
First, select a sky image. Adjust the size to match that of your original landscape picture. "Select all" with your sky image, then "edit-copy." Paste it onto your original image. It will now be in the top layer, whereas we want it in the bottom one. Double click on the background layer, and it will be renamed "layer 0" and can now be dragged to the top.
We want now to select the original sky area. Normally the Magic Wand tool can do this quite well - I normally select a tolerance of 16 and keep shift clicking on the sky till it is all selected. Alternatively, sometimes I use the pen tool for more control to select the sky area.
Next I go to Select-Modify -Expand-2 pixels. This ensures that none of the original sky is left. To make the join less obvious I feather by 2 pixels. Next I press the "Delete" key. The old sky is now deleted, leaving a very unconvincing new one. The tops of buildings on distance hills look unnaturally bright, as they have been lit by the old white sky. The next step cures this.
With the sky area still selected, and the top layer active, go to select-feather and set a radius of 100. Then go to Image-Adjust-Levels. Move the bottom slider to the left. You will see the horizon darkening as you do this. Keep going till you achieve a natural looking balance between the sky and the foreground.
Sometimes the lighting is uneven, so the horizon is brighter on one side of the picture than the other. This is easily fixed. Follow the instructions above up t but not including the levels adjustment. Immediately after feathering, press the keyboard letter "q" to bring up the "Quick Mask" mode. Press "d" to set the default colours of black and white, then do a gradient fill in the selected area starting where you want least darkening and ending where you want most. Press "q" again to exit the quick mask mode and apply the levels adjustment as before. This time the adjustment will be more effective at one side than the other, correcting any uneven lighting.
The above figures are based on files from my 5MP E20 - smaller or larger files will need the amount of feathering adjusted to suit.
As a final touch, remember that skies are always less saturated near the horizon, so check to see if your new sky looks like this. If not, go to your sky layer and do a gradient fill, with the gradient mode set to "Saturation." The foreground can be any fully saturated colour, and the background black or white. If the effect is excessive, just go to "Edit-Fade Gradient" and adjust to suit.
Here are three examples. The first has a bland boring sky.
The next has a more interesting sky added, but looks fake because the horizon is too bright.
The third is processed as described above and looks more natural.
The whole point about Photoshop is to cheat without getting caught, and this is one more way to do it. |
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| Replacing a Sky |
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