Tutorial: Creating a Galaxy in Photoshop
In this tutorial I will explain how to create a relatively realistic looking galaxy with Photoshop. I was searching the web up- and downwards to find any tutorials that could tell me how to get a similar fantastic result. There are like 100.000 planet tutorials out there and the few tutorials which were about creating a galaxy where either very basic or the result looked like everything but a realistic galaxy. The galaxy I wanted should have looked massive and intricate … just like the real ones but with a slightly more artistic touch. I’ve needed a galaxy that I could use as a star map for a space-themed roleplaying game design and the image you see above is a part of the result. Let’s go try to do such one …
There’s a lot to do to create such a Behemoth so let’s get started! I’ve used Photoshop CS3 for this but it should be possible to create this with CS2 and CS1 as well since none of the really new Photoshop features are required. If I do use any of the newer features then there is a way to get the same result in an earlier version, just not with the comfort the latest version offers.
1. Create a new image in Photoshop. The size is up to you but the larger the better, I’ve used a fairly large size of 2800 x 2800 pixels. If you use a smaller resolution be sure to adapt the values I’m using to your image size. Make sure that Color Mode is RGB and the Background Contents is set to transparent. Name the empty layer “background” and fill it with black.
2. Create a new layer and also fill it with black, press ‘D’ to reset the foreground and background color to black and white. Choose Filter/Render/Fibers with a Variance of 20 and a Strength of 4. Then press Ctrl+T to activate the Transform Tool and in the tool’s parameter panel press the Chain symbol to link the width and height values that you now set to 200%. Then enter a rotation value of 45° and commit the transformation. The result can be seen here …
3. Duplicate the fibers layer and transform the new layer again, this time you only need to change the rotation value to 90° and leave the size values like they are. Commit and after that change the new layer’s blend mode to Soft Light.
4. Select the two fiber layers and merge them with Ctrl+E, then go to Image/Adjustments/Levels (or just press Ctrl+L) and enter a value of 70 in the first box, leave the others at 1.00 and 255. Also make sure that Channel is set to RGB. Press Ok. With this we thinned out the white fibers slightly.
5. Currently the image is larger than what we see because we scaled the fiber layer up earlier so let’s get rid of the stuff outside the image area … press Ctrl+A to select all on the fibers layer and cut-paste it back which creates a new layer. After that delete the old fibers layer and rename the new one to “base”.
6. Here comes our secret weapon … go to Filters/Brush Strokes/Spatter and enter a Radius of 25 and a Smoothness of 15. This filter is mostly responsible for the nice wiggly look of the spiral arms later. Now choose Filters/Distort/Twirl with an angle between 500 and 800. This parameter determines how twisted your galaxy will be. I want something with a lot of ‘tracks’ between the spiral arms so I choose 800.
7. The result gives us a whirl with nicely diverse dark and bright lines. Now create a circular selection around it. While dragging hold the Alt key and Shift key to expand the selection around it’s center and keep the aspect ratio. You can also hold then Space key to drag the selection around while doing this. When you got that press Shift+Ctrl+I to invert the selection and then hit Delete to remove the areas around the whirl.
8. With the selection still active choose Select/Modify/Expand with a value of 100 and after that Select/Modify/Feather with a value of 40 pixels. Press Delete two times to smooth out the border of our whirl and then press Ctrl+D to deselect all. Here’s the result. It still looks like everything but a galaxy, don’t worry, we will get to it …
Creating the Structure
9. Let’s start shaping our galaxy out of this what looks like a messed up vinyl record. This part is where it’s getting interesting. First duplicate the “base” layer, name the new layer “outer galaxy” and hide the original layer, we keep it to create more diverse layers later. Use Filter/Brush Strokes/Spatter with the same values like before, Spray Radius 25 and Smoothness 15 and after that give the layer a Gaussian Blur with a Radius of 1 to smooth out the noise that Spatter generated. Then apply Filter/Sharpen/Sharpen to regain some sharpness.
10. Now we are going to remove the black areas from this layer and also thin out the structure slightly … Choose Select/Color Range and pick the black color from the outer area of the image, then crank the fuzziness fully up to 200. Click Ok and then press Alt+Ctrl+D and set Feather to 2 pixel. Again hit Ok and press Delete 4 or 5 times to thin out the black areas between the spiral arms. It can be helpful here to hide the selection edges (View/Show/Selection Edges). Don’t forget to press Ctrl+D to clear the selection after that. Here’s how it looks so far …
11. Next let’s create some glow. Duplicate the “outer galaxy″ layer, rename the duplicate to “glow” and move it under the original layer. Use Gaussian Blur with a Radius of 50 and set the opacity to 60%. Also now set the opacity of the “outer galaxy″ layer to 50%.
12. If you check out some astronomical photos of galaxies you’ll notice that they get more dense toward their center so let’s do that too! Duplicate the “base” layer, rename it to “inner galaxy 1”, move it up to the top and press Ctrl+T and transform-scale this layer down to 70%. You can enter the values in the tool’s parameter palette and the resized layer content will stay centered perfectly. After that use the Spatter Filter again like you did before on the “outer galaxy” layer. Use Gaussian Blur with 1 pixel radius, then sharpen once and then again thin out the black areas like you did before in step 10 with the Color Range selection tool, just this time only press Delete two or three times. Set the layer’s blend mode to Screen and the opacity to around 55%.
13. We need to fatten up our galaxy a little more. Let’s create three more layers as in step 12, always take the “base” layer as the source and every time scale them down a tad more and increase their opacity. I’ve used scale 50% and opacity 80% on the next layer named “inner galaxy 2″, then scale 38% and opacity 90% on “inner galaxy 3″ and scale 32% and opacity 95% on “inner galaxy 4″.
14. Not bad but it looks kind of dull right now so let’s add some contrasting highlights! Duplicate the “outer galaxy” layer and rename the new one to “highlights”, then set it’s blend mode to Screen and it’s opacity to 100%. Press Ctrl+L and enter 160 in the left box. Press Ok and our highlights are finished. Here’s a preview of the current stage and the existing layers …
My God, it’s full of stars!
15. Let’s add a bunch of stars next! Creating diverse and realistic looking star fields is a whole topic unto itself so I’m not going into detail here how to create one. I recommend checking out this tutorial by Greg Martin to create some really fantastic star fields. For the sake of brevity I’ve prepared a star field template which you can download here.
Create a new layer named “stars”, copy the star field image into it and set the blend mode of this layer to Screen. Then Ctrl-Click on the “outer galaxy” layer to create a selection of it. Switch to Quick Mask Mode and draw with a black soft brush in the areas of the image where you want to have stars left. Leave Quick Mask Mode again, press Ctrl+Shift+I to invert the selection and then – with the “stars” layer still selected – hit Delete to remove all stars that are not within the selection. Increase the Brightness of the stars by 50 with Image/Adjustments/Brightness-Contrast. Finally let’s remove most of the black area that is still on the stars layer. Choose Select/Color Range, pick up the black color from the outer areas and decrease Fuzziness to something around 70, click OK and hit Delete twice and clear the selection. The following image shows the selection in Quick Mask Mode and the result of this stage …
16. We still have a strange looking hole in the centre where galaxies normally have an immense cluster of gas and stars so we are going to create the galactic core now … Create a new layer, name it “core” and grab the Brush Tool with a large, soft brush and a white color. A 600 pixel brush works well for this image size. Click seven to eight times in the middle of the galaxy then increase the size of the brush to 900 and click four more times. Finished is our core!
17. So far our galaxy is only black and white and we could have went from the beginning with colors but to make things easier I went without colors so far. Now there are many ways to go about coloring the image. For example we could grab a stylus and graphics tablet and hand-draw colors into the galaxy by using a brush with various blend modes or we could color layer by layer. That’s what I’m going to do now.
Select any of the galaxy layers and press Ctrl+B to bring up the Balance palette and change the colors to your liking. You might want to go for the shadows and leave the highlight untouched to get a better look. You could also duplicate layers, blur them slighly and color these instead or in addition to their original layer. Or you could merge several of the galaxy layers together and color them at once which can look quite good.
18. Currently we are looking top-down onto the galaxy but what if we want to look at it like seen from a window of a spaceship that approaches the galaxy (remember the last scene from Empire Strikes Back?!)? We will change the perspective of the image. The Distort tool under Edit/Transform is what we want for this! Try to distort the image like on the following screenshot. You only actually need to move around the upper and lower left corners. You can flatten your image for this or put all the layers into a layer folder and use the Distort tool on that folder which works as well.
19. This looks a lot better but something seems not right. The whole thing looks more like a flat disc than a voluminous star cluster so we are going to bulge out the core of the galaxy to make it look more realistic. Photoshop’s Liquify tool is actually perfect for this. Time to flatten your layers together now (except the background), then enter Liquify over the Filter menu, select the Forward Warp Tool and a relatively large brush (350) and off you go. Start bulging out the core towards the top-left like in the following image and after that you might want to choose a smaller brush size and reconstruct the area above the upper edge of the core with the Reconstruct Tool.
That’s basically it! Of course these steps are not set in stone. You could experiment with different values or use the Liquify tool early on the base layer to add slight irregularities etc. Your imagination is the limit! Here’s the resulting image and the other galaxy from that you already saw a piece earlier …