- This tutorial does not use images from the latest version of GIMP. Screenshots may be outdated.
GIMP, short for GNU Image Manipulation Program, is a popular free, open-source image editor. It is available for Windows, OS X, and Linux, and requires less resources than editors like Photoshop. The program is known for a steep learning curve but offers a wide range of functionality, with new plugins constantly being developed by its userbase. This line of tutorial pages is planned to explain the various tools and filters, how selections, layers, and masks work, tips for making art in GIMP, and more.Before you start experimenting with GIMP, it may be wise to create a completely new image by pressing File > New or + . You can also import an existing image using the top section of the File menu, or with standard keyboard shortcuts like + .
The absolute basicsMany of the basic concepts in GIMP are easier to figure out when you have the Toolbox open. To open the Toolbox, press Windows > Toolbox or + .
The Toolbox contains all of GIMP's basic tools, the color switcher, and other dialogs, such as Tool Options, represented as dockable tabs.A simple configuration of Toolbox, Tool Options, and Layers will work well for this tutorial. To open Layers, press Windows > Dockable Dialogs > Layers or +
In GIMP, images are represented as series of layers. You can think of a layer as a transparent sheet of paper. You can draw on the layer, but depending on its properties and content, parts of the layers below may be visible.
Layers also don't have to be the size of the image; their layer boundaries can be bigger or smaller, and positioned anywhere in or outside of the image. (Only layer content within the image boundaries, or the canvas, will be visible.)
So instead of thinking as a GIMP image as a paper with a picture on it, think of it more as a stack of transparency papers, with pictures on each of them, and all within a frame.You can create a new layer using Layer > New Layer... or + + , but the quickest way may be to +click the page icon at the bottom of the Layers dialog. Usually, exporting an image from GIMP using File > Export or + results in a flattened file without any layer data. To save the image as a collection of layers that can each be operated on later, save it in GIMP's native XCF format: press File > Save As or + + , and make sure that .xcf is the file extension.
A Channel is a component of a layer that determines an aspect of its pixels' colors, put on a scale from 0 (completely dark) to 255 (completely bright). These will almost always be Red, Green, and Blue, which can be mixed on a computer screen to create any other color.
A Channel you may not be as familiar with is Alpha, which determines opacity. This represents how transparent a pixel is, on a scale from 0, completely transparent, to 255, completely opaque. You can see lower layers through translucent pixels.
Alpha is useful to work with, but layers don't necessarily have this Channel. In the Layers dialog, layers with bold names have no Alpha Channel. To add it, right-click the layer name, then press Add Alpha Channel.
A region that is translucent on all layers will show a dark checkerboard pattern. GIMP uses this pattern to represent transparency. The checkerboard pattern will not appear if the image is exported.
You can restrict the maximum value of a Channel using masks. To add a mask for a layer's Alpha Channel, right-click the layer name, then press Add Layer Mask.... You can then edit the mask.
Switch between editing a layer and its mask by clicking their icons in the Layers dialog. The layer mask is to the right, and is always represented in grayscale.
When you want to edit a specific phrase in a word processor, such as Microsoft Word, you highlight the phrase to select it before you use the command. This is similar to how selections work in GIMP, but it works on pixels instead of letters. To put selections in the simplest possible terms:
If a selection exists, actions on the layer will only be applied to the selected region.Selected regions don't need to be contiguous. Some tools allow you to hold to add to the selection, or to remove parts of it, letting you select two or more separate parts of an image.
Example uses of selections are creating a selection to limit where you can paint onto a layer; selecting parts of a layer, switching layers, then filling the selection on the other layer; and limiting the parts of an image that filters can affect.When you select part of an image, the selection has a moving dashed line around it, called the marching ants. To show and hide the marching ants, press View > Show Selection or + . You will usually want them to be shown. You can also draw on and edit the selection directly by pressing Select > Toggle Quick Mask or + , where selected regions appear unaltered, and unselected regions have a red filter over them.
Selections are a bit more complicated than the simplest possible terms suggest, as the selection is really just a special temporary Channel. This means that you can give pixels a varying degree of selectedness, from 0, unselected, to 255, completely selected. The marching ants are a contour line at 50% selectedness. Actions on partially selected pixels only applied to the degree that they are selected.
Don't worry if this seems a bit confusing; the most basic selection tools use all-or-nothing selection by default.Selection is an important concept to understand, so try to familiarize yourself with the options under the Select and Tools > Selection Tools menus. To clear your selection, press Select > None or + + .
UndoingThe greatest boon of making art digitally is that you can undo mistakes. In GIMP, even selections can be undone. To undo the latest action, press Edit > Undo or the standard + . To redo an undone action, if no other action has occurred since undoing it, press Edit > Redo or + .
The length of the Undo History is limited by device memory, and you will have less undos after large operations. However, you will usually have at least two or three undos to work with.An image's Undo History will be lost if it is closed. There are also certain operations that can't be undone. Be careful and consider working on a duplicate of your image if you want to try something risky. To duplicate an image, press Image > Duplicate or + . Undo History doesn't copy to the duplicate, so only work on the duplicate until you're sure of what you're doing.
A quick but vital note on pasting images into GIMP is that doing so will not paste an image immediately. Instead, GIMP creates a Floating Selection, allowing you to move the content around before committing to the paste, but barring you from most actions.To merge the Floating Selection onto the previously active layer or mask, press Layer > Anchor Layer or + . To paste the Floating Selection into a new layer, press Layer > To New Layer or + + .
In this section, many of GIMP's various tools, and their functions and categorizations, will be discussed.The Toolbox contains a pair of boxes containing the current foreground and background colors. You can click on a color to open a dialog to change it. Many other tools allow you to hold to use the background color instead of the foreground color. To swap the foreground and background colors, press the double-arrow icon, Tools > Swap Colors, or . The default colors are black and white, in the foreground and background, respectively. To reset the colors to these defaults, press the icon of black and white squares, Tools > Default Colors, or . Other than this, you can find many tools both through the Toolbox, the Tools menu, and keystrokes that sometimes use the key.
The Notes column gives some useful tips relevant to the tools, but it is not a comprehensive list of functionality. Try holding down different modifier keys or scrolling through the Tool Options dialog to find other options.
|Tool||Keystroke||Tools menu category||Description||Notes|
|Rectangle Select||Selection||Select a rectangular region by dragging between opposite corners.||
|Ellipse Select||Select an elliptical region by dragging between bounds.|
Good for approximating rounded edges.
|Free Select||Select a hand-drawn region with free and polygonal segments.||
|Fuzzy Select||Select a contiguous region on the basis of color.||
|By Color Select||+||Select regions with similar colors, regardless of their contiguity.|
Good for editing all matching pixels at once.
|Bucket Fill||+||Paint||Fill selected area with a color or pattern.|
Good for coloring line art.
|Blend||Fill selected area with a color gradient.||
|Pencil||Hard edge painting using a brush.|
Good for pixel art.
|Paintbrush||Paint strokes using a brush.|
|Eraser||+||Erase to background or transparency using a brush.|
|Airbrush||Paint using a brush, with variable pressure.|
Good for shading.
|Smudge||Smudge selectively using a brush.|
|Align||Transform||Align or arrange layers and other objects.||
|Move||Move layers, selections, and other objects.||
|Color Picker||N/A||Set colors from image pixels.||
|Zoom||Adjust the zoom level.||
|Text||Create or edit text layers.||