GIMP stands for GNU Image Manipulation Program. The GIMP is a program for manipulating raster graphics similar. As a 'CAD' program it allows limited drawing and editing but its real strengths are for image editing. It is very useful for manipulating and modifying scanned images, images from digital cameras, generating layer-based animated images etc. The gimp can read and write in a large variety of image formats including gif, jpeg, tiff, pix, bmp, png, pnm, xmp and many more.
The GIMP is quite similar to the well known program Photoshop by the Adobe company. However the GIMP is deeply rooted in the traditions of the 'user-freed-computer'. It is released under the gnu public license;
so source-code, user-modification and sharing privileges of the program are a part of using GIMP. The GIMP is one of the shining examples of open-source/user-freed-computing at its best. It is developed and maintained by a worldwide team of talented and altruistic volunteers. All are welcomed to join which can be done via the
Gimp website.
GIMP also has a rapidly-evolving cousin known as
Film-Gimp
which is used in motion-picture editing.
The gimp icon/logo is shown in figure using-gimp1 below.
(Remark: this is an introductory course on the GIMP. It is itself part of a seminar of an introductory course on using Linux. The GIMP is versatile and capable program that this brief-introduction will probably do little justice to. Multi-seminar courses are available through our training group here. If you are interested please contact us via the the contact us
link below. Also books on the GIMP are available via Basis Volume's bookshop. This again is reachable via the contact us link below.
Figure using-gimp1: The friendly icon used to denote GIMP.
Obtaining and installing the GIMP
The latest version in source-code of GIMP can be obtained from the gimp's website http://www.gimp.org
Compilation and installation instruction are available with the source-code. The average user either installs GIMP during Linux installation or installs it via binaries (i.e. rpm, deb et al packages).
Starting the GIMP
On a typical Linux installation the GIMP is launched after either of the following :
Selecting GIMP from a menu accessible from the 'Start' button. On most Linux distributions this is usually an entry under the Graphics menu.
Clicking on the GIMP icon ( shown in figure using-gimp1.) either on the desktop of the bottom tool-bar,
Typing gimp in a command shell or application Launcher (if the user is using KDE).
The GIMP user Interface
When the GIMP is launched it usually generates the dialogs shown in figure using-gimp2.
Figure Using-gimp2: (Left)-A typical startup gf GIMP 1.4: four dialogs and 'A Tip Of The Day' dialog are opened. (Right)- Typical startup dialogs of the recently released Gimp2.X.
Here we are considering the interface to Gimp1.4:
The 'Tool Options' dialog (top Left ): this shows the selected tool in the main pallet immediately below.
The 'GIMP toolbox' (bottom left), this shows the tools available as well as important drop- down menus.
The 'Layers' dialog (top middle); this shows the the layers that make up the picture.
The 'Brush Selection dialog' (top right); this shows the brushes that have been selected on the right of the main main pallet on the bottom left.
The 'Tip of The Day' dialog gives useful tips; for the average user, this is usually closed.
The main dialog (or GIMP Tolobox ) is shown in figure using-gimp3. It provides the tools for image manipulation and as well has two important drop-down menus.
Figure using-gimp3: (Left) - The main GIMP tool pallet. (Right) - Dialogs showing How Foreground colour and brush type are selected in GIMP.
The main-toolbox/tool pallett is shown on the left in the figure above. The functions include:
The top row generally is for selection of a section of the image.
The bottom right cell shows the selected brushes.
The bottom right shows the selected colours in background and foreground.
The function of each button of the toolbox is revealed when the mouse is passed over the button.
Selected buttons on the toolbox are considered later.
The GIMP user interface: The main toolbox File menu
The main-toolbox File-menu has options for file-creation and file-opening. The File-menu is shown below in figure using-gimp4.
The New option generates a dialog for creation of a new image. This too is shown in the next figure.
The 'empty' image is created with the background colour of that of the toolbox at the time of file creation. An example of a new image (created with the dimensions shown) is shown on the right of the figure.
Figure using-gimp4: (Left) - The GIMP File menu pallet. (Centre) - the new image creation dialog generated from the GIMP file menu. (Right) - An example of a new image; the dimensions are those shown in the centre dialog.
The Open option on the File menu generates the 'Load Image' dialog for file selection. This is shown in the next figure. The top of the Load Image dialog has buttons for : (a) creation of directories (b) deletion of files and (c)renaming of files. It also has drop-down-menus:
The Determine File Type drop down menu which reveals the list of file-types that can be opened by the GIMP.
A file-system navigation menu for fetching the file-(this is slightly different in Gimp2).
The Acquire option: (This menu also shown in the next figure.) It can be be used to acquire images from a locally-attached or network-attached scanner using the sane protocol. It can also be used to collect a screen-shot.
Figure using-gimp5: (Left) -The File-opening dialog of Gimp; a preview can be generated below the Files window.. (Right) - The Acquire-image dialog of GIMP.
For image acquisition via a SANE/attached scanner; the option starts the scanner program and returns to GIMP on scanning completion. In the example shown in the above figure, the scanner is an Artec scanner with the SCSI-interface.
The Preferences menu: This generates the dialog shown in figure using-gimp6. It provides overall settings for monitor, environment and session.
Figure using-gimp6: The Preferences dialog of GIMP.
The GIMP user interface : the Xtns menu
After the File-menu, the next drop-down menu is the Xtns-menu. This (among other uses) provides links to external programs and 'plug-in' programs that can interact with the gimp. For example there are plugins available via the Xtns menu that allow text to be generated in a circular arc.
Using GIMP: loading and modifying images
Images can be loaded using the file menu of the main dialog as shown in figure using-gimp5 above. If an image has already been loaded, right-clicking on the image reveals a context menu. (This pop-up or context menu is a feature of the GIMP user-interface). The context-menu's top top entry is the File menu for fetching and saving files. The 'context menu with the File-sub-menu are shown in figure using-gimp7. An opened image file appear as shown in the figure also.
Figure using-gimp7: (Left) -An instance of the GIMP's file menu/context menu. (Right) - An example of a file opened in GIMP.
In the example of an image file opened in the GIMP shown above, the image is surrounded by horizontal and vertical rulers. The filename is at the top and bottom of the dialog. The enlarged dialog shows also the resolution at the top.
Sizing images
Right-clicking on the image invokes the context-menu. A commonly used feature is the scaling of images. The procedure is shown in the figure below.
Figure using-gimp8: (Left) -Example use of Image-menu to modify the size of an image. (Right) - The scale image dialog of GIMP.
With the scale image dialog of GIMP, the required width or height is entered in the labelled box in the Pixel dimensions area. Other settings can be made in the Print Size and Display Unit area or the defaults accepted.
The next figure shows the two images. The leftmost is the original image.
Figure using-gimp9: (Left) -Example of Image scaling in GIMP. ( The scaling dimensions are in the dialog shown in figure using-gimp8.)
Using the GIMP: flipping and rotating images with the Tools menu
The Tools menu is a very useful menu for rotating and transforming images. The Tools menu and Transforms tools plus resulting sub-menus are evoked by right clicking on the image as before. The procedure for flipping an image is shown in figure using-gimp10. Image and flip-ed images are also shown in the figure.
Figure using-gimp10: (Left) -Example use of the Tools/Transforms Tools/Flip menu in GIMP. (Right) - Example use of the flip tool in gimp.
The flipping could also be done using the
selection on the main toolbox. The toolbox is considered in more detail later.
The Tools Menu can be used to rotate an image. The Tools/Transform Tools/Transform is invoked by clicking on the image. The procedure is shown in figure using-gimp11.
Figure using-gimp11: (Left) -Example use of ot the Tools/Transforms Tools/Transform menu in GIMP. (Right) - The Transformation dialog for setting accurate rotation angle for image rotation in GIMP
The transform mouse-prompt can be used to rotate the image or more accurate settings can be set in the dialog and the Rotate button pressed. Figure using-gimp12 shows the rotation of the image.
Figure using-gimp12: Example of image rotation in GIMP. (The rotation angle was set in the dialog on the right in the previous figure.)
Using the GIMP: applying colour
Colour can be changed by selecting an area by one of the select tools on the top of the Main toolbox (figure using-gimp3) and clicking on the paint can on the toolbox. This applies the colour in the foreground. An example of use of this is illustrated in figure using-gimp13.
Figure using-gimp13: Example use of the select in and applying foreground colour tool in GIMP.
Using the GIMP : the Edit menu
The Edit-menu is normally heavily used in GIMP. Is invoked as before by right clicking on the image. An example Edit menu and sub-menus are shown in figure using-gimp14.
Figure using-gimp14: The Edit menu of GIMP. It is a heavily used menu. The Undo utility is particularly useful.
The image can be copied, cut and pasted using the Edit-menu. If a new image is created after a cut or a copy that follows the selection of a section ( using the Rectangular area-select (see below) tool of the main toolbox,) the new image has the dimension of the pre-selected area.
A very useful feature of the Edit menu is the Undo option at the top of the menu. It is particularly useful when moving objects. The moving tool is described below.
Using the GIMP: the main GIMP Toolbox revisited
All the tools on the main tool-bar are important. But the casual user of GIMP will find some tools more useful than others. Below are the most common tools for the casual user of GIMP.
Figure using-gimp15: Icons on the Gimp-1.4 toolbox.
Using the GIMP's more advanced features
Only a very rudimentary use of GIMP(1.4) is covered here. Not covered are areas such as
Working with layers,
working with text,
basic drawing,
making animated graphics such as animated GIFS.
These are covered on our GIMP course using GIMP2.x. If you are interested please contact us via the link below.
For information about Linux resources (books, machines and interface cards) available from Basis Volume please browse the
b-vol website. and click on b-vIT.
This 'how-to' is an excerpt from our introduction-to-Linux course.
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