In contrast with photography where you can work on images that have been produced by any kind of digital devices, GIMP offers the possibility to create image data using drawing and painting tools. This data can be non-continuous tone or continuous tone image data. And of course both types of image data can exist in your project at the same time.
You can create pixels where pixels (image data) do not exist, or you can alter pixels where pixels already exist. These tools may be used in both types of original image data -- from images taken out of devices either/or from images from scratch.
This Lesson attempts a logically structured introduction on the basic concepts of painting in the GIMP. The paint tools are very powerful and in order to be effectively used they demand your full devotion. Let me frankly tell you that i am not any kind of expert in painting and my intention is to help you get an idea of what they can do for you. Are you really interested in digital drawing or the so-called digital art?
- If yes, your second step will be the GIMP's documentation.
- Your third step will be the acquirement of a decent drawing tablet.
- Your fourth step will be to delve into specific online recources, according to your special interests.
Using a drawing tablet (digitizer tablet)
The paint tools are ideally to be used with a drawing tablet, not just with an ordinary computer mouse or pointing device. GIMP has been made taking into account the cooperation of the computer with a drawing tablet. The subtle control of the stylus and the sensitivity of the pressure and motions in combination with the parameters of the GIMP's tools can do wonders in the hand of an experienced person.
In order to make your digitizer device usable in the GIMP, you must install the device on the computer, do the basic configuration of the device on the system, and then inside the GIMP your way to go is Edit > Preferences > Input Devices > Configure Extended Input Devices....
Using the paint tools creatively
The use of these tools is very difficult to be taught, relying on both theoretical knowledge and practice. It is going to be a matter of things like personal taste, skill on using the equipment, imagination, experience. If you want to be good with digital art, you have a long and interesting way to go. You must experiment a lot with the brushes and a decent drawing tablet, your efforts paying off little by little, discovering new tricks that extend the possibilities of physical painting. Not everyone is interested in digital painting, and let me tell you that i do not happen to be one. Using this article here as a guide, you can find websites with specific information and ideas on how to use GIMP for digital painting.
Linear drawing and freehand painting at your fingertips
So in order to use a paint tool you need to perform two actions:
- select the tool (via the submenu Tools > Paint Tools..., via clicking on the Toolbox, or via a keyboard shortcut),
- click or click_and_drag on the active layer.
The outcome will depend on quite a few things:
- the color or pattern or source area,
- the options for the tool,
- the options for the brush,
- the options for the dynamics,
- the layer's properties,
- the type of image,
- the activated channels.
If you simply click_and_drag with your (mouse) pointer, you draw freehand. If you hold down SHIFT after the first click on the drawable, you draw straight lines -- that is to say you do linear drawing. If you hold down CTRL together with SHIFT, the line is constrained at 15 degrees positions -- thus drawing with precision horizontally, vertically, diagonally etc. If you have the View > Snap to Guides option checked, you can use guides for absolutely precise positioning with any drawing task.
The CTRL as key modifier
When a paint tool has been selected the CTRL key alters the function of your pointer:
- Pencil, Paintbrush, Airbrush, Ink: it toggles the pointer to an eyedropper, so that you pick a foreground color clicking on the active drawable.
- Eraser: it toggles the pointer to an eyedropper, so that you pick a background color clicking on the active drawable.
- Note: in these selection actions GIMP remembers the previous click position so that you can go on with your drawing line.
- Clone: it sets the source area.
- Blur/Sharpen: toggles the convolve type of the tool on the fly.
- Dodge/Burn: toggles the type of action.
Common options of the paint tools
- Mode: your painting acts like if the pixels you throw affect your drawable like in a layer mode.
- Opacity: controls the "strength" of the pixels you thraw. Note: for the Eraser it acts the opposite way.
- Brush: you select shape/size of the brush. The Ink Tool has special "procedural" brushes. For the Pencil, Paintbrush and Airbrush you can apply color brushes, while for the rest you use just the "intensity" of the brush.
- Aspect ratio: you can play with the relation of width/height of the brush.
- Angle: you can turn around the clock the shape of the brush.
- Dynamics: that is where the big fun begins. You can correlate specific parameters of the brush with parameters of your pointer device. Basically they apply for a drawing tablet, but some of them for a mouse as well. The basic parameters of pressure and velocity of the pointing device may vary along a stroke, thus offering possibilities for creatively sophisticated strokes. In the dialog area called Dynamics options you can play with the parameters of the paint stroke.
- Apply jitter: it "scatters" the paint during the stroke.
- Smooth stroke: it tries to even the anomalies of a line you create with the mouse or by hand.
- Incremental: you can set if you want repetitive paint thrown on the same area inside the same stroke.
The paint tools
These are accessible in two places:
- From the Toolbox (by default the last 13 ones),
- From the submenu Tools > Paint Tools > ...
After selecting a paint tool, you click on a bitmap layer on your image and holding down you move the pointer, like if physically painting with a brush on a surface. If the layer is not a bitmap but a vector layer, it will be automatically converted to a bitmap layer. The result of your action will take into account options residing in three places:
- the tool's options - you access them by doubleclicking on the tool's icon,
- the brush - you access it by doubleclicking on the active brush icon,
- the paint dynamics options - in the tool's options dialog - they intervene in the painting action in some ways.
The four tools Pencil, Paintbrush, Airbrush and Ink resemble the physical action of painting with color. The first three of them may be considered to be the basic brush tools, while the rest use a brush to affect the pixels of a layer in specific ways:
- The Bucket Fill Tool fills up a layer or selection with a color or pattern.
- The Blend Tool fills with a "gradient pattern".
- The Eraser Tool deletes pixels or makes them semi-transparent.
- The Clone Tool copies image data from a pattern or from a drawable on another drawable or on the same drawable.
- The Perspective Clone Tool alters the perspective.
- The Healing Tool corrects local "defects".
- The Blur/Sharpen Tool blurs/sharpens locally.
- The Smudge Tool flattens pixel values locally.
- The Dodge/Burn Tool affects the luminosity locally.
Using the paint tools in "linear" fashion
Except from using these tools manually on a drawable, you can use them in an "automatic" way on the boundary of a selection or on a path, and this action is called stroking as been explained in Lessons 9 and 15 respectively. You can perform stroking with any of the paint tools, and with the specific options for the specific tool, and the paint dynamics included.
The Brushes
A brush is implemented as an image that defines the color/shape/size of the stroke of a paint tool on a bitmap layer. GIMP has 10 tools to not simply "paint" but affect a layer's pixels in specific way: erase, copy, smudge, lighten, darken etc. All tools except the Ink Tool use the same brushes. The brush defines the area on which the tool will affect layer's pixels while your pointer hits the layer. The outcome of this contact will depend on the layer, the tool and the brush.
GIMP comes with quite a few brushes. You can download ready-made brushes from the web, or you can create your own. GIMP can use different types of brushes, as explained in the documentation, with which you can do absolutely crazy things and become an absolutely crazy artist.
One more good thing is that anytime you perform a copy/cut action on image data inside the GIMP, your application puts the content of the clipboard at the first position in the Brushes dialog -- and you can use it as an actual brush right away. The Clipboard Brush is explained in Lesson 11.
Folders for brushes
With Edit > Preferences > Folders > Brushes you can see the two default folders from which GIMP reads brush files on start. If you have your set of brushes, a way to go is to always keep a special folder inside your personal archive, and copy this folder inside the user folder (in Windows 'Documents and Settings\User\...'). To have your brushes available in any case, you do not have to restart GIMP, just rightclick inside the Brushes Dialog and click Refresh Brushes. This should work fine in case you run GIMP portable on a foreign computer.
Proceeding with the paint tools in action
So in case you are interested in digital drawing and art, i suggest now that you proceed with your second step: the GIMP's documentation on the following tools/topics one by one in detail.
- The Bucket Fill Tool.
- The Blend Tool.
- The Pencil Tool.
- The Paintbrush Tool.
- The Eraser Tool.
- The Airbrush Tool.
- The Ink Tool.
And in the next and last Lesson of this School, you will meet the last tools inside the GIMP's Toolbox.
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