In this Pixelmator tutorial I’m going to take one of the most famous photographs of all time and grunge it up very slightly using some very simple techniques. Do feel free to experiment with this tutorial a bit along the way to achieve (potentially) a better result than the one that I have!
Step 1 - Canvas and Image Size
Make a new document. I'm going to choose the size of my screen, 1440x900 pixels as I might like to use this as a wallpaper. Your choice.
Drag the blue marble image into the document. Resize it so it fits within the document that we've created by pressing ⌘F and changing the 'size' parameters in the top of the document window. Select 'constrain proportions' or you'll turn our planet into a big sausage. When it's down to a manageable size, you can use the resize handles instead and center it in the middle of the document.
Step 2 - Background
We want to get rid of the background of the planet. This will enable us to add effects right up to the planet's edge. Luckily, this is easy to do with this particular image. Use the 'Magic Wand' tool to select the black edge of the image. Press Delete when you've got the edges selected. You can now use the paint bucket tool to paint the 'Background Layer' black.
Add a new layer below the planet and above the background. Now go to the menu Filter > Generator > Clouds, set white and black as the colours (if they aren't already like that) and hit OK.
Add a new layer just below the planet. Using a big soft paint brush, paint some big colours in as shown below. Make them nice and bold - their effect will be muted in a couple of steps. If you don't feel that your colours 'blend' well enough you can go Filter > Blur > Gaussian Blur to soften the effect.
Set the Blending mode of the new clouds layer to 'Overlay'.
Step 3 - Overlays and Texture
Make a new layer above all the others. Use the gradient tool to make a big, colour to colour linear gradient across the image. I've chosen red and green, but you can use any other colours you want. Set the blending mode of this new layer to Overlay.
Add a new layer just below the Earth's layer. Go Edit > Fill and fill it with 50% grey. This is easiest to achieve when you click the middle 'swatch' in the colours palette, see below for the settings to find this colour. Again, set the blending mode to Overlay. The layer will disappear when you do this - don't panic!
Choose Filter > Stylize > Noise. Add a reasonable amount of noise (not too much, not too little) to the image. This is a great method for add texture to any of your compositions.
I'm not a complete fan of the background. Time to darken it. Make a new layer above the clouds layer and using a big soft black brush, paint over the image. Don't be too consistent - we don't want things perfect, remember! Set the mode of this new layer to Overlay and reduce the opacity slightly.
Select the clouds layer and go ⌘L to bring up the levels screen. Increase the blacks by dragging the swatch over to the right.
Step 4 - Glow Effects
Add a new layer just below the Earth layer. Using a big soft white brush, paint a 'glow' on the upper edge of the planet, as shown in the screen shot below.
Select the Earth layer by clicking on the layer's thumbnail (in the layer palette) while holding down the ⌘ key on the keyboard. Add a new layer above the Earth and create another glow effect, this time on the inside of the planet. The selection will stop you from painting over the edge. Deselect when done by pressing ⌘-SHIFT-D. You can adjust the opacity of this new layer if you want to. Repeat this step on the other side of the planet with a dark brush.
Step 5 - Adjust and Refine
Add this texture to the document. It should be below the planet and the glowing layers that we have added. Desaturate the texture by pressing ⌘U and dragging the Saturation slider to the extreme left. Use the Levels (⌘L) to darken the texture. Set the blending mode of this new layer to Overlay (Overlay mad aren't we?).
The edge of the Earth isn't quite there yet. Select the Earth by holding ⌘ down and clicking on its layer in the layer palette. Go Edit > Refine Selection and drag the feather slider up slightly.
Now you can invert the selection (Edit > Invert Selection) and press the delete key a couple of times to blend the edge of the Earth into the background.
And we're done!
Here is another one I did using pretty much the same techniques, just different colours and a different composition.