5. Brushes

شكل 7.15. Brush strokes example

Brush strokes example

A number of examples of brushstrokes painted using different brushes from the set supplied with GIMP. All were painted using the Paintbrush tool.


A brush is a pixmap or set of pixmaps used for painting. GIMP includes a set of 10 paint tools, which not only perform operations that you would normally think of as painting, but also operations such as erasing, copying, smudging, lightening or darkening, etc. All of the paint tools, except the ink tool, use the same set of brushes. The brush pixmaps represent the marks that are made by single touches of the brush to the image. A brush stroke, usually made by moving the pointer across the image with the mouse button held down, produces a series of marks spaced along the trajectory, in a way specified by the characteristics of the brush and the paint tool being used.

Brushes can be selected by clicking on an icon in the Brushes dialog. GIMP's current brush is shown in the Brush/Pattern/Gradient area of the Toolbox. Clicking on the brush symbol there is one way of activating the Brushes dialog.

When you install GIMP, it comes with a number of basic brushes, plus a few bizarre ones that serve mainly to give you examples of what is possible (i. e., the "green pepper" brush in the illustration). You can also create new brushes, or download them and install them so that GIMP will recognize them.

GIMP can use several different types of brushes. All of them, however, are used in the same way, and for most purposes you don't need to worry about the differences when you paint with them. Here are the available types of brushes:

Ordinary brushes

Most of the brushes supplied with GIMP fall into this category. They are represented in the Brushes dialog by grayscale pixmaps. When you paint using them, the current foreground color (as shown in the Color Area of the Toolbox) is substituted for black, and the pixmap shown in the brushes dialog represents the mark that the brush makes on the image.

To create such a brush: Create a small image in gray levels using zoom. Save it with the .gbr extension. Click on Refresh button in the Brush Dialog to get it in preview without it being necessary to restart GIMP.

Color brushes

Brushes in this category are represented by colored images in the Brushes dialog. They can be pictures or text. When you paint with them, the colors are used as shown; the current foreground color does not come into play. Otherwise they work the same way as ordinary brushes.

To create such a brush, create a small RGBA image:

Select FileNew… from the main menu.

In the Advanced Options, set for example the Color space to RGB color and set Fill with to Transparency.

Draw your image.

Select FileSave… from the main menu to first save your image as an .xcf file to keep its properties.

Select FileExport As… from the main menu to export the image as a brush with the .gbr extension.

In the Brush Dialog, click on the button Refresh brushes .

Your brush appears among the other brushes. You can use it immediately, without restarting GIMP.

[نکته] نکته

When you do a Copy or a Cut on a selection, you see the contents of the clipboard (that is the selection) at the first position in the brushes dialog. And you can use it for painting.

شكل 7.16. Selection to Brush after Copy or Cut

Selection to Brush after Copy or Cut

Image hoses / Image pipes

Brushes in this category can make more than one kind of mark on an image. They are indicated by small red triangles at the lower right corner of the brush symbol in the Brushes dialog. They are sometimes called "animated brushes" because the marks change as you trace out a brushstroke. In principle, image hose brushes can be very sophisticated, especially if you use a tablet, changing shape as a function of pressure, angle, etc. These possibilities have never really been exploited, however; and the ones supplied with GIMP are relatively simple (but still quite useful).

You will find an example on how to create such brushes in Animated brushes

Parametric brushes

These are brushes created using the Brush Editor, which allows you to generate a wide variety of brush shapes by using a simple graphical interface. A nice feature of parametric brushes is that they are resizable. It is possible, using the Preferences dialog, to make key presses or mouse wheel rotations cause the current brush to become larger or smaller, if it is a parametric brush.

Now, all brushes have a variable size. In fact, in the option box of all painting tools there is a slider to enlarge or reduce the size of the active brush. You can do this directly in the image window if you have set correctly your mouse wheel; see Varying brush size.

In addition to the brush pixmap, each GIMP brush has one other important property: the brush Spacing. This represents the distance between consecutive brush-marks when a continuous brushstroke is painted. Each brush has an assigned default value for this, which can be modified using the Brushes dialog.

[ياداشت] ياداشت

GIMP can use MyPaint brushes. Please refer to قسمت 3.11, “MyPaint Brush” for more information.

5.1. Adding New Brushes

[ياداشت] ياداشت

There is a quick method to add a new brush: قسمت 5.4, “Creating a brush quickly” .

To add a new brush, after either creating or downloading it, you need to save it in a format GIMP can use. The brush file needs to be placed in the GIMP's brush search path, so that GIMP is able to index and display it in the Brushes dialog. You can hit the Refresh button, which reindexes the brush directory. GIMP uses three file formats for brushes:

GBR

The .gbr ("gimp brush") format is used for ordinary and color brushes. You can convert many other types of images, including many brushes used by other programs, into GIMP brushes by opening them in GIMP and saving them with file names ending in .gbr. This brings up a dialog box in which you can set the default Spacing for the brush.

A technical specification of the GBR file format can be found on developer.gimp.org.

شكل 7.17.  Save a .gbr brush

Save a .gbr brush

GIH

The .gih ("gimp image hose") format is used for animated brushes. These brushes are constructed from images containing multiple layers: each layer may contain multiple brush-shapes, arranged in a grid. When you save an image as a .gih file, a dialog comes up that allows you to describe the format of the brush. See قسمت 5.2, “Creating animated brushes” for more information about the dialog.

A technical specification of the GIH file format can be found on developer.gimp.org.

VBR

The .vbr format is used for parametric brushes, i. e., brushes created using the Brush Editor. There is really no other meaningful way of obtaining files in this format.

MYB

The .myb format is used for MyPaint brushes. Please refer to قسمت 3.11, “MyPaint Brush” for more information.

To make a brush available, place it in one of the folders in GIMP's brush search path. By default, the brush search path includes two folders, the system brushes folder, which you should not use or alter, and the brushes folder inside your personal GIMP directory. You can add new folders to the brush search path using the Brush Folders page of the Preferences dialog. Any GBR, GIH, or VBR file included in a folder in the brush search path will show up in the Brushes dialog the next time you start GIMP, or as soon as you press the Refresh button in the Brushes dialog.

[ياداشت] ياداشت

When you create a new parametric brush using the Brush Editor, it is automatically saved in your personal brushes folder.

There are a number of web sites with downloadable collections of GIMP brushes. Rather than supplying a list of links that will soon be out of date, the best advice is to do a search with your favorite search engine for GIMP brushes. There are also many collections of brushes for other programs with painting functionality. Some can be converted easily into GIMP brushes, some require special conversion utilities, and some cannot be converted at all. Most fancy procedural brush types fall into the last category. If you need to know, look around on the web, and if you don't find anything, look for an expert to ask.