Setting up GIMP for Artistic work
This tutorial will tell you how to configure GIMP to be more intuitive for artistic work and finishes with you creating a nice little artistic painting. It is divided into several parts. It has been rewritten extensively to also take advantage of the new features of GIMP2.4.x.
1) Setting up keyboard shortcuts in GIMP for easing artistic use This little section gives you some hints on setting up your work environment to ease artistic use. The part about Brush scaling is a new feature of GIMP2.4.x, so that only applies if you are using that or a later version of GIMP.
2) Setting up dynamic parametric brushes. This section helps you create some basic but extremely useful default brushes you'll often want to fall back on. These are what we will use in part 3.
3) Starting out with artistic use of GIMP. Here you start learning how to paint with the powerful airbrush tool by doing a series of small exercises followed by a simple and fun drawing project to create a dead tree. Many have tried this and had a lot of fun with it so far, so don't be shy to post your result!
This tutorial is especially suitable for you who is drawing with a mouse, and doing the exercises herein will hopefully help you getting better at drawing free-hand with the mouse (there are hints for tablet artists as well though). This is unfortunately not something you can just learn a "trick" for, you have to train it like any form of art. I have worked with the mouse in this tutorial to show that you don't require a drawing tablet to achieve nice hand-drawn effects. I use GIMP under Linux Debian but the windows choices etc should work the same under Windows and Mac. The images where taken using GIMP2.2.13, but you should be able to find your way without any trouble. All thumbs are clickable.
1) Setting up keyboard shortcuts in GIMP for easing artistic use(To make sure you have GIMP's interface set up, also take a look at the interface tutorial
here).
A critical thing in GIMP art making is learning to use the keyboard shortcuts. GIMP is very powerful in this regard -- it's easy to assign any keyboard combination to any common function you use.
Make sure you have
Preferences->User Interface->Use dynamic shortcuts selected, then you can just highlight any menu option and press the key you want to use for it. Don't be afraid that you're overwriting some default shortcuts -- a guidline is that if you don't know that shortcut now you won't be missing it later either (and if you do you can just assign a new shortcut). You can find a list of all GIMP's default shortcuts in this
list on gimpusers.com.
The idea when setting up keyboard shortcuts is that you don't want to have to move your "painting hand" away from drawing more than absolutely necessary. Most default ones are ok already, but if you change anyone, go for shortcuts you can press with only one hand (no three-finger combinations across the keyboard).
You also don't want to click on more icons and buttons than you want to -- your cursor should stay on the canvas as much as possible. So if you don't know the shortcuts for the basic tools, you'd better learn them now. You'll be glad you did. Very useful shortcuts for this tutorial are (by default)
A for the Airbrush and
Ctrl-D for the eraser. You'll also be helped a lot by knowing
Ctrl-left-click for picking an existing colour from the canvas (this means you don't have to go to the palette). I also recommend learning or even changing the default shortcuts for the Zoom in/out so you know where they are and are placed next to each other. Other critical shortcuts are
Ctrl+A and
Ctrl+Shift+A for selecting/unselecting all (very useful if you suddenly don't seem to get any results when painting, this often is because of a mistaken selection somewhere), and
Page Up/down to switch between layers. There are many more, but that's up to you and depends on your personal preference.
Keyboard shortcuts for Scalable brushes Next we need to set up your GIMP to handle adjustable brush sizes -- that is, brushes that resize by pressing a keyboard shortcut. With a little training you can then resize your brush, mid-stroke. Traditionally this could only be accomplished by using
parametric brushes, that is, brushes created in GIMP's internal brush editor. Beginning with GIMP2.4.x however, you can now use the "Scaling" feature of the paint tools to rescale any type of brush. The scaling slider is located in the tool options and is available for the Pencil, Paint brush, Eraer, Airbrush, Clone tools, Healing tool and Blur tool. It is currently not available for the Smudge tool (this will come for GIMP2.6).
Go to
Preferences->User Interface->Configure Keyboard Shortcuts You will get a list of various command types to which you can assign shortcuts. Choose
Tools and scroll down to the part involving "brush scale". You should assign keyboard shortcuts at least to "Increase brush scale" and "Decrease brush scale". Choose keys next to each other, so you can handle them with one hand only.
2) Parametric brushes setup A
parametric brush is a brush that is described by a mathematical formula, not an image (also called a "vector brush" in some places). The advantage of them is that they always look the same no matter how much you scale them. If you for example where to use the "Scale" function to scale up a circular brush a lot, you would eventually see it become jagged around the edges. A parametric brush, on the other hand, you can scale up as much as you want and it will always be that perfect circle, since it's just a mathematical formula describing how it should look. The disadvantage is that parametric brushes can only take simple geometric forms, but for most digital painting this is more than enough. Despite having hundreds of brushes in my brush folders, the simple round hard brush is still the one I use the most. A range of parametric brushes are great to have for any artistic use, just like a regular painter always need to have some basic brushes lying around no matter how advanced he is.
The parametric brushes coming by default with GIMP cannot be rescaled by a keyboard shortcut. To achieve that we need to create new ones using GIMP:s brush editor. Also note that the operation for rescaling a parametric brush is
different from the normal brush scaling command we saw in the previous section. This means you need a separate keyboard shortcut for it, as seen below.
So first choose to create a new round brush with the Brush editor. Make one with maximum hardness. The actual value of the "Radius" is not so important here -- this you will be able to adjust with a keyboard shortcut. This brush is by far my most often used brush, and coupled with changes in opacity and using various tools it can be used for practically any effect if you only have a little patience.
The brush list is ordered alphabetically. The brushes you create now will likely be your standard brushes in the future, so save them with names starting with aa, so you know it will end up at the top of the list. I saved this first one as "aa_custom1" (if you have many brush sets loaded, you might have to use something like "000_custom1" instead to make sure you end up at the top of the list).
Next create a fuzzy brush by decreasing the hardness value. This is an excellent brush for applying all sorts of effects like smoke and fog. It can also be used very effectively with airbrush or the smudge tool to create perfect colour blends. Save this as aa_custom2, and it will end up next to your first brush.
It can be useful to have a "caligraphic brush" of variable size. Generally the ink tool is better for actual calligraphic work (since 2.4.x the Ink tool can also be resized by keyboard control if it's set up in the preferences). This brush is useful for situations where you need to draw a sharp oblique angle, something which can be hard to do even with a small round brush. I actually have two such brushes, angled differently (angled 45 and 135 degrees respectively). Name them appropriately. You want to have a shorter spacing for this brush, to create a continuous line.
Finally, a square brush. This is very powerful for creating technical forms and structures, like houses, bulkheads and anything that should have a 90 degree edge or corner. Once again, the size (radius) doesn't matter, since the brush will be adaptable. Name it a good name, like "aa_custom5".
Now to set up GIMP to be able to adjust the brushes quickly. Go into the preferences->Interface and choose the "Context" sub-list. This is the context-sensitive setup, which is rather unused in GIMP's default setup.
There are a lot of interesting settings you might want to add keyboard shortcuts to in this menu, but the ones we're interested in for now are the Decrease/Add radius settings.
Assign keys to these by just clicking the entry and then the key-combination you like. My choices are probably not what you'd want to use, since I have it set up for operation with the keys on my tablet. You want to assign keys to all the entries I show in this image. The increase/decrease radius changes the radius of the (user-created) brush by a very small amount, allowing for detailed adjustments. The "Increase/decrease Radius more" steps up in faster steps, which is also very useful sometimes. Pick keys you think you can reach and use easily with
one hand -- that is, the hand you're not holding your mouse in (That is why my Alt++ combination is not suitable for you -- you'll need two hands to put that combo in on the keyboard -- unless you have a tablet with programmable buttons of course).
Another convenient thing is the "Next Brush" / "Previous Brush" entries, that allows you to flip back and forth in your brush list without actually moving your pointer over there to click on it. This command and the brush resize commands are, next to the zoom, probably the commands you'll use the most during freehand artistic work (is for me anyway), and you'll be hitting those buttons all the time. So make sure you pick keyboard shortcuts that suit you.
For drawing tablet users with command buttons and/or touch strip on the tablet: The buttons on the tablet usually work the same as "Ctrl", "Space", and "Alt" buttons on the keyboard (you can configure this separately for the tablet though). Assign these in clever ways to make GIMP do clever things when pressing those buttons (The "zoom" functions are neat to have directly on the tablet for example). If you have a touch strip too, assigning the strip to various button combinations can allow you to change brush sizes, brush types, zoom and even adjust RGB values without having to move your pen off the canvas. 
To make sure you can easily see the changing brushes, make sure "show brush outline" is selected in Preferences->Image windows. Also activate the crosshair ("Show paint tool cursor"). The reason for this is because if the brush resizes to becomes very small you might loose sight of it if you don't have the crosshair activated.
Remember to save your settings.
Try it out! Choose one of your self-made brushes and resize it up and down. Step through them with your new shortcut.
This setup will help you when using all common drawing tools that use brushes. For now we concentrate on the airbrush tool however.
3) Starting out with artistic use of GIMP using the airbrush tool and adjustable brushes
Choose the airbrush tool by pressing the right key on your keyboard. ("a" by default).
Choose some decent Rate and Pressure. This is much a matter of testing out things. Go with my settings if you like. Note the 50% opacity set for the tool. This is a very useful setting and personally I never use the airbrush with any higher opacity than this (rather I'd go even lower, actually).
For tablet users: The "Pressure sensitivity" section describes the result of pressing the pen down harder on the tablet. For normal use, all boxes are usable except Colour, which is kinda specialized since it translates the pressure into a position in your currently selected gradient. It's worth experimenting with, but we won't see any use for this in this tutorial.
The rate and pressure set by the bottom sliders will influence the sensitivity of the tablet. The more boxes you have checked, the more involved the airbrush tool becomes and the more effects you can achieve (since it better emulates a real brush) -- but it'll possibly also become harder to handle. Temporarily flipping on/off especially opacity and/or hardness is often useful when wanting to create varying effects. This is much a matter of preference. 
Now, it's time to begin using the airbrush tool. This is where practicing comes in. Open the image above so you can see the details of each airbrush stroke while reading below. Then try to repeat and practice this as much as you can. Your hand on the mouse will quickly become steadier, you'll see.
Begin by picking a red tone and the hard-edged brush. Do straight lines vertically and horizontally, in a grid pattern. Try to make as straight lines as you can. Depending on how steady a hand you have, it can be hard to do this with a mouse, but moving it upwards is often easier than going horizontally. Notice how the colours will grow darker in the intersections -- you have colour scaling even without picking a new colour from the palette! Scale down the size of the brush by pressing the keyboard shortcuts you chose before and try it again. Notice how fine and sharp the lines look, despite using the airbrush tool. Try to make the lines as straight as possible, not crooked as I did.
Observe: Of course you could also use the Shift-click/Shift-drag combo to create straight lines. But the point of this exercise is NOT to teach you how to draw straight lines per se -- but to help you get steadier with the mouse (and learn the peculiarities of the airbrush doing so). Learning to master your mouse to draw straight lines "freehand" is an important step towards eventually handling more complex shapes and curves. Freehand drawing skills helps both when doing selections and gives that loose natural look you need for "artistic" style work as we will do last in this tutorial. When you feel confortable drawing horizontal and vertical lines with the mouse, try drawing them to an angle. Still try to make each as straight as you can. Note how you can overlap the lines several times and the colour will only become richer and richer. Try to work with a lower opacity set in the Airbrush tool if you want, so you can see the effects.
Next pick a blue colour and the "fuzzy brush". Do the same with this brush, to get a feel for what it can do. Once again, notice how the smallest resized brush in blue still appears rather sharp to the eye.
The "Caligraphy brushes" I tested in two tones of green in the image. They are special in that they change size depending on in which direction you draw them. They work well for creating sharp angles and, they can be used to create fuzzy effects, something which the Ink tool cannot do. Try to do some scribbles in green as I have done to get a feel for them.
Finally, the square brush. I used orange for this. Try to create sharp angles and corners with it. Resize and play around.
Finally, try to mix three colours with the airbrush. Pick a clean red and scribble with a large brush. Note how the colour changes and that you don't have to choose any new colour in order to get a lighter red -- just avoid painting over certain areas more than once or twice to retain a lighter tone. Do the same with Blue and Green and make them overlap here and there to see it shine through. (Admittedly I also smudged the center together in my image, to mix even more). The important point here is noticing the amount of different shades you are getting while only choosing three colours from the palette and essentially using but one single tool being pulled back and forth over the same area over and over.
Now try to use the resizing during drawing. Draw a line, resize, draw the next line. Try to do it faster and faster until you have the feeling in your hand.
Finally we'll try some rough sketch with the airbrush tool, using 3 colours only. We will create a dead tree. This is just a sketch, so don't go about deleting or undoing anything you draw, even if it looks odd. Just play with sweeping the airbrush in straight lines, using whatever lines you happen to put down.
Pick a faint pink and fill the background with that using the fill tool.
Then take the hard brush we created and size it up a fair bit. Choose a bright blue colour. Only use that one color from now on, don't pick any other shades of blue -- let the airbrush handle shading for you.
Sweep out vertical lines, just as before, just draw more lines in the center than at the edges, so it'll become darker. Resize the brush and pull out some other straight lines for the branches. Resize the brush as you get further and further out on the branch to make smaller and smaller twigs.
With a rather small brush, make some parts of the trunk sharper, along the edges for example.
Finally, pick a white colour (the 3rd colour we'll use) and with small strokes you apply white at strategic places to bring out parts of the trunk and branches. Copy my lines if you want, but remember this is just a sketch, so don't worry about details. You can use this as a base to create detail later if you want -- but that's another tutorial.
Using the mouse to draw takes practice, but that practice is as much a matter of having a steady hand than anything else. Doing simple things as just drawing straight lines over and over will quickly improve your skills. Curved lines is much more difficult, but can be done too, even though this is where a drawing tablet really starts to shine. Note that you can do a lot with straight lines though, essentially a curve is nothing more than a lot of straight lines if you just use the zoom tool enough ... The tree you should actually be able to do with just straight lines (this is why I picked that example).
Try to make the dead tree for yourself, and show your results!
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Was this tutorial too easy for you? Or do you feel you've mastered the airbrush by now?
There is now a second tutorial covering more advanced airbrushing techniques, you can find it
here.
Other Art tutorials by me (few of them at least): Forest background,
Drawing Cyborgs,
Penciling characters,
Adding light and mood,
Paint a futuristic city,
Draw an eye in 5 minutes (video)Full list of GIMP art tutorials by me-----
.
Griatch
EDIT: To show an example of what can be done developing such a simple sketch, I added some more to it (very quick thing, mind you):
Picture Host - PicTiger-----
From the thread: Neil:
Gargoyle:
rover789456:
redwagon2020:
Ti-Louis:
http://img321.imageshack.us/img321/728/deathtreejq0.jpg (giving link since image stretched the page)
FlyingPenguin:
Gus:
megadyptes:
Furicuri55:
ArchGoat:
Azamath:
a saurus1:
Luigi239:
niteflite:
Sir Yeti:
vero:
KittyTwizz81:
obrien:
lorenzo:
Jacob:
dr-fish:
FSX:
vivaldiscool:
Linkmasta23:
Dakkon:
DrummyRalf:
Azamath:
Cilla:
Boba Fettuccini:
MarkSparrow:
bloodwolf:
Wilber:
Suxx:
Qvadrat:
