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Photoshop Effects with Clouds  - or

Photoshop Clouds and Difference Clouds Filters

category: graphics, digital photography and image editing

Photoshop's Clouds filter creates a fill of random haze between the foreground and background colors using Perlin-based fractal noise resembling natural clouds. The Difference Clouds Filter creates a cumulative effect exactly like duplicating the Clouds results layer and applying the difference blend mode. Colors can be intensified by pressing and holding the shift key while applying these filters. Any repeating texture made with Clouds and Difference Clouds will tile perfectly if you use image dimensions based on powers of two, such as 128, 256, or 512 pixels. OK, that's cool, but what can you do with these filters?

Well, to start with, you can make your own clouds, in your own sky, and replace some of the truly noisy skies found in many otherwise great pictures. In this picture, for instance, the blue portion of the sky is so full of blobby noise that the already disappointingly cloudless sky becomes boring by the time you blur out all the noise. Also, what makes this picture interesting are the clouds hanging in the valley. Wouldn't it be interesting if a cloud were passing above the valley cloud cover, right in front of us.

First, let's replace the sky. Drop out blue with the Blend If sliders and create a mask that isolates the sky. (see entry Advanced Masking by Dropping Out Colors) Add to the mask by painting a little black, at low opacity, in the transitional area between the mountains. Duplicate your image layer and make your new mask into a layer mask on that duplicate layer. Then, set your forground color to the darkest blue in the sky and the background color to the lightest using the eyedropper. With the Gradient Tool, using a foreground to background gradient, drag to replace the sky.

Now, let's make the clouds. Create a new layer, set your colors to default black and white, and swap to white over black. Choose Filter, Render, and then Clouds. Repeat with Ctrl+F until you see something you like. Run Levels on your cloud layer to increace the contrast a little. Switch to the channels palette and, with the clouds layer active, Ctrl-Click on the RGB channel to select the bright areas of the clouds. With the selection active, switch back to the layers palette, make a new layer, set forground to white, and press Alt+Backspace to fill the selected areas with white. Turn off the visibility of your Clouds Filter layer, and you will see your new white clouds everywhere. We don't want them everywhere, but we'll take care of that in a second using a layer mask. First, let's give the clouds a little more body.

To give the clouds more body, click on the original Clouds Filter layer. Select all (Ctrl+A), copy the layer, create a new channel, and paste it into the new channel called Alpha 1. Return to the Layers Palette, create a new layer, and fill it with white. Choose Filter, Render, and Lighting Effects, set the texture channel to Alpha 1, and adjust the light to show from above while using an angle to bring out the texture of the clouds. Click OK. Set this layer to the Multiply Blend Mode. Go to the white, but flat, clouds layer and Ctrl-Click to select the clouds. With the selection active, return to the Lighting Effects layer and press the Delete Key. Depending on the angle of your lignting, you might need to apply a slight blur to this layer to smooth out the effect. Choose Filter, Blur, then Gaussian Blur and adjust the Radius slider.

The Layers Palette should now contain, from top to bottom, the Lighting Effects layer, the white clouds layer, the original Clouds Filter layer (which you can now trash), the new sky with its layer mask, and lastly the original image. Play with the opacity of the top (Lighting Effects) layer until it looks good, Merge Down into the white clouds layer below,and add a layer mask. Remember, you can always go back with the History Palette. Finally, edit the layer mask, painting away any clouds you don't want with black using a soft brush.

He said on 08.12.05 @ 04:27 PM CST