GIMP Class

This class will give you the skills to open, edit and combine images using the powerful program named GIMP.

To Install:

GIMP will likely be installed on your computer already, but if not, you can find it in Synaptic Package Manager under "gimp." Other useful packages are "gimp-data-extras" that include extra brushes and gradients, and the "gimp-help-en" package.

Step One: Different Ways to Open a File

Right-click on the file and choose "Open with...GIMP Image Editor."

If GIMP is running, drag the picture file into the toolbar.

Once a file has been opened, it will appear in a list under "Open Recent" in the File menu, so you can find your recent work easily.

Step Two: Intro to GIMP history

Everything you do can be fixed

GIMP makes a mistake as easy to fix as the keyboard shortcut "ctrl-z." The motto is: Try it, you can undo ;)

The only time you cannot undo the human motion during certain processes, like the paintbrush or free-select tool. You can undo the whole mouse-stroke, once the button is released, but you cannot go back to specific portions of the stroke.

GIMP keeps extensive undo history, which can be a toolbar tab or a separate floating window. And if you "undid" but you wish you didn't, the "Redo" command will restore you back to before the undo. You can even undo an undo.

Step Three: The Toolbox

The box with all the little icons is the toolbox. Each icon offers a quick way to select different tools for manipulating images.

We'll start with the top-left tool in the toolbar, the square. This is the basic selection tool. It can be used to draw a box around and capture a specific portion of an image. To use the tool, select the tool in the toolbox by left clicking on it, move the mouse icon to the image, then left click and drag the box around the portion of the image that you want to capture. Once the box is created you can move the edges to fine-tune your selection by clicking and dragging on the corners of the box, or clicking on the edge and using the direction keys for more control.

Once you have made your selection, it will have trailing lines around it, and you will be able to copy it to the clipboard with "Ctrl-C" to use in another image or to make into a new layer. You may also manipulate the selection like its own layer, but you can only work with one selection at a time, where you can work with as many layers as you want. More on layers below...

The entire top row of tools are basically derivations of the selection tool. You can select elliptical objects, draw a free-hand selection around something (very difficult), and do a fuzzy select which will deduce objects and select them by matching colors.

The next tool selects by color, selecting regions that match even if they are apart.

The scissor icon uses "intelligent edge-fitting" to select objects from images.

Skipping a couple, the eyedropper tool is a color selector. Use it to find colors you like in your photos to use for filters, text or painting.

The zoom tool looks like a magnifying glass. Click on the image to zoom, ctrl-click to zoom out. You can also draw a box of where you want to zoom. I personally prefer the keyboard shortcuts "+" and "-" on the Num Pad to zoom in and out.

The measurement tool, a compass, is a helpful way to measure objects, layers or selections in your images.

You can move layers and selections using the Move tool. It looks like two blue crossed arrows.

We'll skip the alignment tool, going on to Crop, the logo of an exacto-knife. This tool is an easy way to trim down an image. Draw a box, resize it by dragging the corners, and when you're satisfied, click in the middle to crop to the box. Especially useful after you've used Rotate, the next tool, to straighten a crooked snapshot.

The Rotate tool, a square rotating, allows you to rotate individual layers, selections or paths separately from the rest of the image, or the whole image.

The next four tools work much the same way. The Scale tool is used to resize the image, layer or selection.

Shear tool "tilts" the image or selection.

Perspective is a fun tool to change the perspective of the image or selection.

Flip simply reverses the image or selection, horizontally or vertically.

We'll hold off on the rest of the tools until GIMP 2 in order to explain the vital resource that allows you to control each tool's option: the toolbar.

Step Four: The Toolbar

The Tool Options and so much more

The toolbar can have many tabs. We will only cover some of the tabs here.

The main tab is the Tool Properties tab. The icon looks like a tiny mixer board.

When you select a tool in the toolbox, that tool's options will be displayed in the toolbar. Each tool will perform a function without changing any options, but most options will dramatically change the properties of the tool. Experiment with the options! You can always undo ;)

Step Five: Working with Layers

With layers, you can apply effects to specific parts of the image while leaving the rest unchanged.

Creating a New Layer

If you want to add a new image as a new layer, simply drag and drop it into your image window. You will see it appear as its own layer in the Layer toolbar. If you can't find your Layer toolbar, you can add it as a tab to your Tool Properties toolbar area under your main toolbar.

You can rename layers by double-clicking on the name in the Layer toolbox. Type the label you wish and hit "enter" to complete.

For a new blank layer, choose Layer>New Layer from the image menu, which will pop up a dialog giving you an option to name the layer and adjust its properties. Name the layer whatever you want and ensure it will be a Transparent layer. Finish by clicking OK when done. Draw on your new layer without affecting your original image!

The text tool automatically creates a new layer for the text, but more on that in GIMP 2 :)

Working with Layers

You can paste an image from the clipboard, which can come from any other image or program that will let you push "Ctrl-C" or "Copy to Clipboard." The pasted image will appear as a floating selection (with trailing lines around it) until you anchor it onto the next layer down with the anchor button in the Layer toolbox. If you want the new image to be on its own layer, click the new layer button on the lower right of the Layer toolbox to make the floating selection into a new layer.

If you want to see "under" the layer momentarily, you can make the layer invisible by clicking on the Eye icon in the Layer toolbar. Click the empty box to make the layer visible again.

If you wish to see "through" the layer permanently, on the Layer property, select the layer and adjust the Opacity slider. This enables you to easily "blend" images together.

Step Five: Freeki Filters

Because we are working with Layers, we can add effects to the Background and "upper" Layer separately. Try it out! Extract a piece of an image, make it a new layer and turn it Day-Glo. The options are only limited to your imagination.

GIMP has a huge number of effects and filters and that list continues to grow. The main list is found under "Filters." Experiment with these! Don't forget, it is easy to undo anything, so go ahead and try things out. In class, we will go over a few of my favorite filters if we have enough time.

Hopefully, these skills will give you the confidence and footing to begin to explore the possibilities that GIMP can offer you! Good luck!

Jackson