by Máirín Duffy
Welcome to the second installation of The open palette. Last time, we focused on creating orbs and 3D text using Inkscape’s new blur filter. This month, we’ll be focusing on creating brushes for the Gimp using Inkscape.
Gimp brushes can be used as ‘stamps’ to rapidly create multiple copies of the brush shape; they can be smeared across the canvas; they can be tiled across the entire canvas to create unique textures. You can generate new artwork from the ground up or manipulate photos (think sparkle brushes applied to a photo of a person’s eyes) and other graphics using Gimp brushes. They are also very versatile tools because of the ease with which they can be created and customized.
The Inkscape techniques introduced in this tutorial are especially useful for creating shapes for Gimp brushes, but these techniques can also be used in creating unique shapes for other applications as well. Conversely, the kinds of shapes we’ll be generating for the ‘Grungy’ brushes we create in this tutorial are, of course, not the only kinds of shapes you can use to create Gimp brushes. At the end of this tutorial, you’ll find a list of suggestions with some examples of other types of Gimp brushes you can create using some of the basic techniques outlined in this article.
Installing Inkscape and the Gimp
You may follow the instructions in our previous article to install Inkscape. Installing the Gimp is just as easy in any version of Fedora:
yum install gimp
Please refer to http://gimp.org/downloads/ for instructions on how to download for other Linux distributions and other operating systems.
Now that you have the software you need, we’ll begin!
Create your base bitmap texture
First, we’ll need a grungy, scattered vector texture to break down into basic shapes that will serve as the building blocks for all of the different types of brushes we’ll end up creating.
The easiest and best way I have found to create these textures is to use Inkscape’s bitmap trace tool on a simple texture bitmap. The Gimp comes with a great set of default patterns that we can use to make the texture bitmap we need.
- Open up the Gimp. Create a new document canvas; let’s make one that is 420px x 300px.
- In the Gimp toolbar, select the bucket tool.
- Using the Tool Options dialog (Shift + Ctrl + T, or Dialogs > Tool Options in the canvas file menu), select the ‘Pattern fill’ radio button underneath ‘Fill Type.’ I selected the ‘Burlwood’ pattern – you may do the same or you may pick whichever texture suits your fancy!
- Using the bucket tool, click on the canvas to fill it with the pattern you just selected. You may notice that the pattern has some seams. Let’s crop the canvas down to the largest size possible that doesn’t show seams!
- Select the crop tool in the Gimp toolbar.
- Start in the uppermost left corner of the canvas, and click and drag the crop tool to the lower right until you’ve got an area without any noticeable seams. Hit your ‘enter’ key or click the ‘Crop’ button in the ‘Crop & Resize’ dialog to finalize your crop.
- Now you have a nice bitmap texture you can use with Inkscape’s bitmap trace tool to pick up some pretty useful shapes. Save your image by using the File > Save As … item in the canvas file menu, and let’s move on to Inkscape!
Download the example bitmap texture created using the steps above: bitmap-texture.png
Trace your bitmap
Open up Inkscape. Import the bitmap texture we just created in the Gimp by selecting the File > Import … item in the Inkscape menu bar. Use the file chooser to select the bitmap texture and click the ‘Open’ button.
- You can also simply drag the bitmap texture file from your Desktop or any Nautilus folder directly onto the Inkscape canvas.
Drag the bitmap texture to the center of the canvas, hit the ’1′ key on your keyboard, and scroll the canvas such that the texture is again in the center of the canvas.
- The ’1′ key is a very useful shortcut. It basically zooms the canvas at 100%, making it easy to see things at their ‘real’ size.
- Next, click on the bitmap to select it, and open the ‘Trace Bitmap’ tool by selecting the Path > Trace Bitmap … item in the Inkscape file menu.
- Hit the ‘Preview’ button in the ‘Trace Bitmap’ dialog to see how your trace will look. You should see some speckles or some items in the preview window. (If you don’t see anything, exit the ‘Trace Bitmap’ dialog, and make sure you have selected the bitmap on your canvas by clicking on it. Then go back to the ‘Trace Bitmap’ dialog and try again.)
- Let’s adjust the ‘Trace Bitmap’ settings and see what kinds of traces we can get – our goal is a trace with a lot of small, discrete shapes. I ended up using the ‘Multiple Scans’ part of the dialog, selecting the ‘Grays’ radio button and unchecking the ‘Smooth’ option. Once you’re satisfied with the trace preview, hit the ‘OK’ button to create the trace and hit the ‘X’ in the upper right corner of the ‘Trace Bitmap’ dialog to close it.
- Select your trace (it will be on top of your bitmap) and shift it a few pixels to the right by holding down the Shift key and hitting the right arrow key. You’ll see your bitmap texture underneath, which you can delete now by clicking on it and pressing the delete key.
If you used the ‘Single Scan’ option in the ‘Trace Bitmap’ tool, skip the next two steps.
Because I used the ‘Multiple Scans’ option in the ‘Trace Bitmap’ dialog, I’m going to have multiple grouped layers of shapes. If you used this option too, select the trace, and hit Ctrl + Shift + G to ‘Ungroup’ these layers. (Alternatively you may use the Object > Ungroup item in the Inkscape menu bar.) Then, select the top layer by clicking on it and shift it to the right so you can view the layers underneath. Do this until you can see each layer. (I ended up with seven layers.)
Select one of your trace layers to serve as the building blocks of your brushes. The ones that will be the easiest to work with will have distinct, interesting shapes in a wide range of sizes. (I ended up selecting the trace layer in the middle left of my screen and I deleted the other layers.)
- Now that you have a trace layer to work with, let’s rip it apart into individual little shapes. Click on your trace to select it, then select the Path > Break Apart item in the Inkscape menu bar. See, right now your trace is one path with many little sub paths; using ‘Break Apart’ will split it into little individual paths.
Generating brush shapes with your trace
- Here is where the fun begins! Lasso around your little shapes by clicking and dragging the pointer tool from the Inkscape toolbar. While they are selected, let’s pay a visit to the ‘Align and Distribute’ dialog. ( Object > Align and Distribute …)
- In the ‘Align and Distribute’ dialog, let’s select the upper leftmost icon to left-align our shapes. After clicking the left-align icon, click on any area of the canvas outside of your shapes to admire your handiwork. (Keep the ‘Align and Distribute’ dialog open.)
- Now, lasso your first (left-align) ‘brush’ by clicking and dragging the pointer tool around it. Then, while the brush is selected, press Ctrl + D to make a duplicate on top of it. Immediately after hitting Ctrl + D, hold down the Shift key and hit the right arrow key several times to move your new copy away from the original brush. (Give it plenty of breathing space.)
- Now, let’s try another alignment on your shapes. Lasso your new brush copy and select the bottom align icon in the ‘Align and Distribute’ dialog. Again, click any area of the canvas outside of your brush to admire your new brush.
- Feel free to keep duplicating and aligning new brushes in various ways at your leisure. Here’s what I came up with just by using the align tools:
- You may notice as you keep playing with the align tool that the little shapes inside the brush keep getting bunched together. Well, you can throw the distribute tools in the mix to make more variations in your brushes. Two of the distribute tools that are particularly good at ‘unbunching’ the shapes are the ‘make vertical gaps between objects equal’ and ‘make horizontal gaps between objects equal’ tools. Duplicate some of your bunched-up brushes and try them out. Another cool distribute tool is the ‘randomize’ tool – be sure to give it a try as well.
- Keep manipulating you groups of shapes using combinations of the ‘Align and Distribute’ commands until you get a good variety of interestingly-shaped brushes. Let your creativity go wild.
- Be sure to save your work as an SVG via the File > Save As … item in the Inkscape menu bar.
I like to arrange the brushes I come up with in a sheet in Inkscape and save them all in an Inkscape SVG file I can import into other projects as I need them.
Download the example vector shapes created using the steps above: shapes.svg
Create Gimp brush files
Why just use your new brushes in Inkscape? Brushes like these can also be made into Gimp brush files that you can use in the Gimp. Here’s an example of how to do this using one of the brushes we’ve created:
- First, open up your brush SVG sheet in Inkscape. Lasso around the brush you’d like to turn into a Gimp brush.
Next, make the brush black by clicking on the ‘black’ color in the Inkscape color palette (along the bottom of the screen.)
- If you do not have a black color in your palette, you may also select black by going to the Object > File and Stroke … item in the Inkscape menu bar.
- Keeping your brush selected, open up the ‘Export Bitmap’ dialog by selecting the File > Export Bitmap … item in the Inkscape menu bar.
In the ‘Export Bitmap’ dialog, make sure the ‘Selection’ button at the top of the dialog is selected. Click the ‘Browse…’ button to open up a File Chooser window to select where to save the bitmap to, and give the bitmap a name in the ‘File Name’ text entry widget.
- The Export Bitmap dialog only exports bitmaps in *.png format, so use a *.png file extension as in the screenshot.
- Your work in Inkscape is done. Fire up the Gimp, and open up the *.png file you just exported from Inkscape with it. Select the Image > Flatten Image item in the canvas menu bar, and then select the Image > Mode > Grayscale item in the canvas menu bar. (These steps will allow you to change the color of the brush as you use it later.)
Now, choose the ‘Save As …’ item in the ‘File’ menu of the *.png file’s canvas. Click on the ‘Select File Type’ expander widget, and select the ‘Gimp Brush’ file type (you’ll have to scroll a bit to find it.)
- a quick shortcut is to simply add a ‘.gbr’ file extension to the image when you save it.
After you click ‘Save’, you’ll be prompted to choose a Description for your brush. Be aware that this description is what you’ll identify the brush by in the Gimp ‘Tool Options’ dialog, so give it a good one. Don’t worry about the spacing setting as you can always change it as you use the brush.
- Alright, you have a Gimp brush file now! All you need to do is load it into the Gimp. The easiest way to do this is to go into your home folder using Nautilus, and selecting the View > Show Hidden Files option so it is checked. Look for the .gimp-2.2 folder, and go into it.
Inside the .gimp-2.2 folder, you’ll see a brushes folder. You can simply drag your brush *.gbr file into this folder.
- You may also want to go back to the View > Show Hidden Files item in your home folder in Nautilus. All of those little . folders clutter up my home folder in Nautilus and tend to drive me nuts!
- Open up the ‘Brushes’ dialog by clicking Shift + Ctrl + B on your keyboard. Hit the ‘Refresh’ button and select the brush tool in the Gimp toolbar.
- In the ‘Brushes’ dialog, click on the left arrow icon in the upper right (this will open a control menu for the dialog.) Select the ‘View as List’ radio button in the menu that appears. Now all of the brushes listed in the dialog will be listed in alphabetical order and their names will be displayed. Select the brush you created in step 6 above. (Hint: When you saved the brush, you were prompted to give it a name. It will have this same name in the brush selection menu here.)
- Go wild and have fun with your new brush! You can change the color of the brush as well as the spacing its given when you drag it across the palette using the ‘Brushes’ dialog. You can also share the *.gbr file with your friends.
Create a new file in the Gimp (pretty much any size will do). Select the brush tool in the Gimp toolbar.
Other brush ideas
We used Inkscape’s bitmap tracing and align and distribute tools to create vector shapes that we then turned into Gimp brushes. However, you can convert any vector shape you create in Inkscape into a Gimp brush. Here are some examples of brushes you could make next:
Create star shapes in Inkscape and turn them into Gimp brushes you can then use to decorate a drawing or photo of the night sky.
Take a photo of yourself, use Inkscape’s bitmap tracing tool to create a vector version of the photo, and turn it into a Gimp brush, creating many multi-colored clones of yourself on a Gimp canvas.
Create several spiral brushes from vector shapes created by Inkscape’s spiral tool and use the brushes to dress up a photo in the Gimp.
Here is a set of 23 brushes created from all of the brush shape variants created with the Inkscape Align & Distribute tool as part of this tutorial: