The RRU Gimp Tutorial

Configuration

The GIMP is highly configurable. Many features may be set via the Preferences dialog, available off the GIMP's main File menu. This dialog should be self-explanatory, but we'll cover it, anyway.

You may also change the preferences by editing various files; the GIMP uses gimprc and gtkrc, both found in $HOME/.gimp/ . These will be described after the Preferences dialog.

The Preferences dialog reads data from both the system gimprc and a user's personal .gimprc file. Saving the preferences updates the user's personal .gimprc file. Only settings actually changed in the Preferences dialog will be saved. This gives the system administrator an easy way to make global changes, but also means that behavior may suddenly change if a new version of the GIMP is installed.

The system gimprc file location may vary between installations; the default is in /usr/local/share/gimp/gimprc . If you need to find this file and it's not there, you need to talk with the person who installed GIMP on your system.

The user's personal .gimprc file resides by default in $HOME/gimp/.gimprc .

Preferences

The GIMP comes with a fairly extensive preferences editor. Preferences can be applied just to the current session with the [OK] button, or saved permanently with the [Save] button. Even if you don't read through this section, you should glance at the Preferences panel.

Four sub-panels are available: Display, Interface, Environment, and Directories.

Display Preferences

Image Size

The Image size parameters (width and height) define the size of a new image in pixels. Set these to whatever value you expect to use most frequently for new images.

TIP: If you use (or expect to use) a different image size every time you need a new image, set the Image size parameters to something fairly small; you'll be overwriting them, anyway, but if you just hit [OK] for a new image, you won't waste a lot of memory and screen real estate. If you find you need something larger, you can always change your preferences!

Image Type

The GIMP comes configured with RGB as its default image type. You may change this to Grayscale if you prefer. Indexed is not supported as a default image type, since so few operations work rationally on it.

Preview size

This sets the size of the preview image used by many plug-ins to show how changes will affect the current image. This impacts not only screen real estate, but the speed of the preview operations; previews on small images will be much faster than previews on large images.

Preview size defaults to Small. It can also be set to None, Medium, or Large

Cubic Interpolation

You can't always get the exact color you want; GIMP (and all other good graphics programs, such as Navigator and xv) use some form of interpolation to choose the best color match.

Normally, GIMP uses linear interpolation. If you are unhappy with the colors in your image (for instance after resizing), you can try setting Cubic Interpolation and trying the offending operations again. Cubic Interpolation wil take longer but sometimes yields much better results.

For details on the various types of interpolation, consult a good graphics reference book.

Image Type and Check Size

The transparent parameters define the appearance of any unedited portion of a transparent layer; this makes it easy to see what is actually happening. You can change the basic background displayed (during editing only, of course) by a transparent layer to any of the checks (as in checkerboard squares, not check marks) provided or to White, Gray or Black. You may wish to create a new panel, add a transparent layer, and play with this option to see how these work. Different options work better with different images. If you are using checks instead of a solid background, you may also change the size of the checks.

Note that these affect only the appearance of transparent layers, not the final image!

Interface Preferences

Undo levels

The undo level simply defines how many operations the GIMP remembers how to undo. Successive undo attempts up to this number should work correctly; beyond this, nothing happens when you attempt an undo.

This defaults to 5. If you expect to need more undo levels, make this as large as you need to, but realize that each undo level requires space to save an image state. Also, nervous fingers on the moue can take you farther back than you intended!

Resize window on zoom

Setting this means that zooming in on an image will cause its window to attempt to expand to contain the whole, zoomed image, and contract when images are unzoomed. Unsetting this means that the window size will not change; scrollbars will appear to let you move around the zoomed image.

You can always use your window manager to resize the window, so this should be set for your defauilt case - do you usually want the window to expand (and contract) as you zoom in and out, or not?

Disable cursor updating

By default, the GIMP changes cursors to indicate state, such as current operations. You may disable this if you find it distracting, or if your system slows down because of it.

Show tool tips

Tool tips are the little bozes that appear over many controls when the cursor hovers there for very long. By default the tooltips are enabled.

Marching ants speed

Marching ants refers to the moving dashed line around selections. This parameter determines how long to wait between updates (in milliseconds). A slow speeed (large number) makes things look jerky, but a high speed (small number) can use a lot of your system's power, especially on lower powered systems.

This may not work on all systems.

Environment Preferences

Conservative memory usage

One can always trade time for space. If memory is more critical than processing speed (or if limited memory is causing swapping, which drastically impacts processing speed) you should set this parameter, which forces the GIMP to use less memory, at some cost in speed.

Tile cache size (bytes)

I can't really explain this one. The default is 10485760 (1MB).

Install colormap (8-bit only)

Since any image beyond a simple icon or line drawing uses a klot of colors, you can run out of colors fast on a 256-color (8-bit) system. To get around this, you can tell the GIMP to use its own colormap. This is known as a "private" colormap", as opposed to the "shared" colormap all graphics-based applications share by default.

This results in color flashing - the situation where moving your cursor into or out of an app causes the screen to flash, usually making the other apps (including the background) "go technicolor".

If you only run out of colors when GIMP and some other, particular application is up, you may prefer to tell the other application to use a private colormap, instead. Netscape Navigator, for instance, can be invoked with the "-install" (install a private colormap) options:

   netscape -install

Colormap cycling (8-bit only)

One way to make the "marching ants" more efficient is by "color cycling", which simply switches some number of colors (in this case black and white).

The only problem is that this is done in the colormap, which means that the cycled colors are cycled for all on-screen applications, including the window manager. This can be disconcerting, annoying, even painful in some individuals. If things flashing all around you don't bother you, feel free to try this.

Directory Preferences

There are two types of directories the GIMP worries about: personal and shared, ublic directories. For instance, when the GIMP is installed, a set of brushes is installed in a public location such as /usr/local/share/gimp/brushes/ but you as a user can also have brushes of your own in a personal directory such as /home/fred/.gimp/brushes/ .

Private directories (and other personal, GIMP-related files) are normally kept somewhere under $HOME/.gimp/ .

Some of the directories referenced in this preferences panel are simple directories, while others are lists of directories separated by colons.

Temp dir

This is the directory where the GIMP creates any temporary files it needs during operation (other than swap files). Default:

    $HOME/.gimp/tmp

Swap dir

The GIMP caches a lot of data. Rather than just consume all the memory it can, GIMP tries to be intelligent about how much memory it uses. In some cases this means it needs to swap, or copy data to or from disk, while it re-uses RAM. When it does this, it creates a file in the swap directory . (The filename contains the word ``swap'', just in case you ever wonder.) Default:

    /home/meo/.gimp

Brushes dir

This is the list of directories to search for brushes. The default is to look in your personal directory and the standard, public directory, but you can add other directories as necessary: project directories, expansion directories, directories provided by other applications (maybe someday!), whatever. Default:

    /home/meo/.gimp/brushes:\
    /usr/local/share/gimp/brushes

In reality these would be on one line, without the backslash ('\'). They are shown this way to work better with browsers on smaller screens.

Gradients dir

This is the list of directories to search for gradients. The default is to look in your personal directory and the standard, public directory, but you can add other directories as necessary: project directories, expansion directories, directories provided by other applications (maybe someday!), whatever. Default:

    /home/meo/.gimp/gradients:\
    /usr/local/share/gimp/gradients

In reality these would be on one line, without the backslash ('\'). They are shown this way to work better with browsers on smaller screens.

Patterns dir

This is the list of directories to search for patterns. The default is to look in your personal directory and the standard, public directory, but you can add other directories as necessary: project directories, expansion directories, directories provided by other applications (maybe someday!), whatever. Default:

    /home/meo/.gimp/patterns:\
    /usr/local/share/gimp/patterns

In reality these would be on one line, without the backslash ('\'). They are shown this way to work better with browsers on smaller screens.

Palette dir

This is the list of directories to search for palettes. The default is to look in your personal directory, but you can add other directories as necessary: project directories, expansion directories, directories provided by other applications (maybe someday!), whatever. Default:

    /home/meo/.gimp/palettes

In reality these would be on one line, without the backslash ('\'). They are shown this way to work better with browsers on smaller screens.

Plug-in dir

This is the list of directories to search for plug-ins. The default is to look in your personal directory, the standard, public script-fu directory, and the standard, public plug-in directory, but you can add other directories as necessary: project directories, expansion directories, others' personal directories, whatever.

If you add other extensions which use plug-ins, you will need to check whether their installation procedures added their plug-in directories to this parameter. If not, you will need to do so manually before the new plug-ins will work. Default:

    /home/meo/.gimp/plug-ins:\
    /home/meo/.gimp/plug-ins/script-fu:\
    /usr/local/lib/gimp/1.0/plug-ins

In reality these would be on one line, without the backslash ('\'). They are shown this way to work better with browsers on smaller screens.

gimprc file format

The gimprc file format is based on a language called scheme. (Scheme is used all over the place in GIMP.) This means that every non-blank line in the GIMP configuration file is either a comment or a variable setting. Comments begin with pound signs ('#'), while variables are set using parentheses. (NOTE: No equal signs are used to set gimprc or other scheme variables!)

gimprc variable names are all formed of lower case alphabetic characters and hyphens ('-'), also known as dashes. Most of the GIMP preferences variables are of common types - strings, integers, booleans and paths. Paths are strings containing one or more file system paths, where multiple file system paths are separated by colons. Variables of any type other than boolean may include other variables. For the most part you don't care about this, except that you will notice that many paths contain components like ${gimp_dir} (that's how you reference a GIMP variable) . These are defined at the time the GIMP is built; standard builds will default ${gimp_dir} to $HOME/.gimp and ${gimp_data_dir} to /usr/local/share/1.0 . You may override ${gimp_dir} by setting the environment variable GIMP_DIRECTORY .

Variable type	Example
boolean	(install-colormap)
int	(default-threshold 15)
string	(default-brush.gbr")
path	(pattern-path "${gimp_dir}/patterns:${gimp_data_dir}/patterns")
other	(color-cube 6 6 4 24)

The following list contains all the current GIMP variables which may be set in gimprc files. Most of these also appear in the Preferences dialog. A few of them will not take effect for the current GIMP session if set via the Preferences dialog; for these you must restart the GIMP. The last few variables are not used by the GIMP itself, but by extensions or plugins. Most of these names are self-explanatory, but the detailed explanation of each variable (COMING SOON!) should answer any questions as to what a given variable affects. A few of these (such as positions) may be set only in the gimprc files.

Setting	Use	Type	Default
temp-path	path for temporary files	path	"${gimp_dir}/tmp"
swap-path	path for swapping tiles	path	"${gimp_dir}"
menu-path	menu path	path	none
brush-path	where brushes are located	path	"${gimp_dir}/brushes:\ ${gimp_data_dir}/brushes"
pattern-path	where patterns are locatewhere plugins are located	path	"${gimp_dir}/patterns:\ ${gimp_data_dir}/patterns"
plug-in-path	where plugins are located	path	"${gimp_dir}/plug-ins:\ ${gimp_dir}/plug-ins/script-fu:\ ${gimp_plugin_dir}/plug-ins"
palette-path	where palettes are located	path	"${gimp_dir}/palettes:\ ${gimp_data_dir}/palettes"
gradient-path	where gradienst are located	path	"${gimp_dir}/gradients:\ ${gimp_data_dir}/gradients"
default-brush	the default brush	string	"19fcircle.gbr"
default-pattern	the default pattern	string	"wood2.pat"
default-palette	the default palette	string	"Default"
default-gradient	the default gradient	string	"German_flag_smooth"
gamma-correction	monitor gamma correction	double	1.0
color-cube	color cube definition	reds greens blues grays	6 6 4 24
tile-cache-size	the amount of memory allocated for tile caching	size	10M
marching-ants-speed	the number of milliseconds between updates of moving dotted lines for selections	int	300
undo-levels	number of levels you can undo	int	5
transparency-type	type of transparency	0 - 5 (see below)	1
transparency-size	the size of the transparency checks (pseudo-background)	0 - 2 (see below)	2
install-colormap	whether to use a separate colormap for the gimp	boolean	false
colormap-cycling	whether to use colormap cycling for the marching ants	boolean	false
default-threshold	seed-fill pixel intensity difference threshold	int	15
stingy-memory-use	whether efficient memory usage is more important than speed	boolean	false
allow-resize-windows	whether windows auto-resize when zooming in or out	boolean	false
cursor-updating	use context-dependent cursors	boolean	true
no-cursor-updating	don't use context-dependent cursors	boolean	false
preview-size	size of preview in layers dialog / selector	none, small, medium, or large (see below)	small
show-rulers	show rulers around images	boolean	true
dont-show-rulers	don't show rulers around images	boolean	false
ruler-units	units rulers display in	pixels, inches, or centimeters	pixels
auto-save	doesn't currently do anything!	boolean	true
dont-auto-save	doesn't currently do anything!	boolean	false
cubic-interpolation	use cubic interpolation (better quality) rather than linear interpolation (faster)	boolean	false
toolbox-position	toolbox position	position	0 0
progress-position	progress bar position	position	170 5
info-position	info dialog position	position	165 0
color-select-position	color selector dialog position	position	140 120
tool-options-position	tool options dialog position	position	0 345
confirm-on-close	confirm if closing without saving an image	boolean	true
dont-confirm-on-close	don't confirm if closing without saving an image	boolean	false
show-tips	show "Tip of the Day" dialog	boolean	true
dont-show-tips	don't show "Tip of the Day" dialog	boolean	false
last-tip-shown	index of last tip shown (you probably don't care!)	int	-1
default-image-size	default image size for new images	width height	256 256
default-image-type	default image type for new images	RGB or grayscale	"RGB"
plug-in	???	???	name
plug-in-def	???	???	name
show-tool-tips	show tool tips when cursor hovers over a control	boolean	true
dont-show-tool-tips	don't show tool tips when cursor hovers over a control	boolean	false
Used only by their respective programs
script-fu-path	location of script-fu scripts	path	"${gimp_dir}/scripts:\ ${gimp_data_dir}/scripts"
gfig-path	location of gfig data	path	"${gimp_dir}/gfig:\ ${gimp_data_dir}/gfig"
gflare-path	location of gflare data	path	"${gimp_dir}/gflares:\ ${gimp_data_dir}/gflares"

Last updated: 27 March 1999

Miles O'Neal, <meo@rru.com>

11501 Johnson Rd / Leander, TX / 78641-5823