| 3. Paint Tools | ||
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第 14 章 工具 |  |
| 3. Paint Tools | ||
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第 14 章 工具 | |
To access these tools, select → from the main menu.
The GIMP Toolbox includes fourteen “paint tools”. By default they are shown together in five groups, but this can be disabled in Toolbox Preferences by unchecking Use tool groups.
图 14.27. The Paint Tools in the Toolbox
The default view groups similar tools together. The paint tools groups are inside the red square.
The paint tools in the toolbox in ungrouped view inside the red area.
The feature they all have in common is, that all of them are used by moving the pointer across the image display, creating brush-strokes. Five of them behave like the intuitive notion of “painting” with a brush. Pencil, Paintbrush, Airbrush, and MyPaint brush are called “basic painting tools” or brush tools.
The Pencil Tool.
The Paintbrush Tool.
The Airbrush Tool.
The Ink tool.
The MyPaint Brush Tool.
The other tools use a brush to modify an image in some way rather than paint on it:
the Bucket Fill Tool fills with color or a pattern;
the Gradient Tool fills with gradients;
the Eraser Tool erases;
the Clone Tool copies from a pattern, or image;
the Heal Tool corrects small defects;
the Perspective Clone Tool copies into a changed perspective;
the Blur/Sharpen Tool blurs or sharpens;
the Smudge Tool smears;
and the Dodge/Burn Tool lightens or darkens.
The advantages of using GIMP with a tablet instead of a mouse probably show up more clearly for brush tools than anywhere else: the gain in fine control is invaluable. These tools also have special “Pressure sensitivity” options that are only usable with a tablet.
In addition to the more common “hands-on” method, it is possible to apply paint tools in an automated way, by creating a selection or path and then “stroking” it. You can choose to stroke with any of the paint tools, including nonstandard ones such as the Eraser, Smudge tool, etc., and any options you set for the tool will be applied. See the section on Stroking for more information.
Holding down the Ctrl key has a special effect on every paint tool. For the Pencil, Paintbrush, Airbrush, Ink, and Eraser, it switches them into “color picker” mode, so that clicking on an image pixel causes GIMP's foreground to be set to the active layer's color at that point (or, for the Eraser, GIMP's background color). For the Clone tool, the Ctrl key switches it into a mode where clicking sets the reference point for copying. For the Blur/Sharpen tool, the Ctrl key switches between blur and sharpen modes; for the Dodge/Burn tool, it switches between dodging and burning.
Holding down the Shift key has the same effect on most paint tools: it places the tool into straight line mode. To create a straight line with any of the paint tools, first click on the starting point, then press the Shift key. As long as you hold it down, you will see a thin line connecting the previously clicked point with the current pointer location. If you click again, while continuing to hold down the Shift key, a straight line will be rendered. You can continue this process to create a series of connected line segments.
Holding down both keys puts the tool into constrained straight line mode. This is similar to the effect of the Shift key alone, except that the orientation of the line is constrained to the nearest multiple of 15 degrees. Use this if you want to create perfect horizontal, vertical, or diagonal lines.
Many tool options are shared by several paint tools: these are described here. Options that apply only to one specific tool, or to a small number of tools, are described in the sections devoted to those tools.
The Mode drop-down list provides a selection of paint application modes. As with the opacity, the easiest way to understand what the Mode setting does is to imagine that the paint is actually applied to a layer above the layer you are working on, with the layer combination mode in the Layers dialog set to the selected mode. You can obtain a great variety of special effects in this way. The Mode option is only usable for tools that can be thought of as adding color to the image: the Pencil, Paintbrush, Airbrush, Ink, and Clone tools. For the other paint tools, the option is always disabled. A list of modes can be found in 第 2 节 “Layer Modes”.
In this list, some modes are particular and are described below.
The Opacity slider sets the transparency level for the brush operation. To understand how it works, imagine that instead of altering the active layer, the tool creates a transparent layer above the active layer and acts on that layer. Changing Opacity in the Tool Options has the same effect that changing opacity in the Layers dialog would have in the latter situation. It controls the “strength” of all paint tools, not just those that paint on the active layer. In the case of the Eraser, this can come across as a bit confusing: it works out that the higher the “opacity” is, the more transparency you get.
The brush determines how much of the image is affected by the tool, and how it is affected, when you trace out a brushstroke with the pointer. GIMP allows you to use several different types of brushes, which are described in the Brushes section. The same brush choices are available for all paint tools except the Ink tool, which uses a unique type of procedurally generated brush. The colors of a brus
