Hitchhiker's Guide to GIMP: The Free Image Editor

Quick note: If you haven’t read Younite’s Guide to Illustrator please do, it’ll provide more insight into how image editing works in a more professional environment. Most professional graphic designers use Photoshop/Illustrator rather than a free program like GIMP, which is still a powerful tool but not as widely used in the industry.

Installation


Installation of GIMP is rather easy, just go to https://www.gimp.org/ and hit the big red “Download” button. This will automatically bring you to the download page of the most recent version.

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On the following page, you should see 2 download buttons specifically for the OS that you are on. Click the orange “Download GIMP directly” button as it is unlikely you have BitTorrent or have any clue as to what it is so it’d be easier for you to follow along with a direct download.

After that just launch the installer and follow the installation instructions in the Setup Wizard, mostly just clicking Next and Finish, and then you will have GIMP fully installed.

Please note: GIMP supports Windows 7 and OS X Yosemite or higher as well as a plethora of Linux operating systems. If you use an older operating system you may want to download an older version of GIMP but this guide may not apply to you in that case.


Setup


Once you launch GIMP you should be greeted by this screen.

To create a new file go to file > new and set the dimensions you want and it will automatically create an image with a white background of that specific size.

To open an existing file go to file > open recent or file > open depending on if you have recently opened it with GIMP or not.

To paste in a new image use Ctrl+V to paste it into the current image, or a new one if no images are currently open, or Ctrl+Shift+V to paste into a new image.

Please note: Pasting an image with a transparent area will fill in the transparent areas with black, I’m not sure why GIMP does this but it always has as far as I can remember.

To change the layout of GIMP, simply drag and drop the tab headers(the area highlighted in red) and drop them anywhere on your screen that you want them.

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Dropping them in the middle of the screen will create a floating toolbox which you can then reposition and resize to fit your needs. To place it along the right-side of the screen simply move your cursor all the way to the right or slide open the dock by clicking and dragging on the 3 dots on the right of your screen and then dropping the tab in the dock.

Tools


GIMP provides you with all the tools you should need for basic image editing/designing purposes. For simplicity sake I will just name the tools I find most useful and describe their purpose without getting into the details of all of their tool options. Hovering over a tool will display the tool’s name and description so it should be easy to find what you need.

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Please note: for many tools hitting Enter will perform some sort of action. For example: on the path tool it will connect the last node to the first and make the area a selection, for the crop tool it will crop the image, etc.

Rectangle Select Tool(R): Lets you select a rectangular regional of the layer.

Eclipse Select Tool(E): Lets you select an elliptical region of the layer.

Fuzzy Select Tool(U): This is your magic wand tool, use it select all connecting areas in a layer of similar color within a certain threshold.

Select by Color Tool(Shift+O): Lets you select all areas in the layer that are of similar color within a certain threshold.

Path Tool(B): Lets you select a region of the layer with a freeform shape defined by nodes. Click to place nodes that connect with a straight line, Click + Drag to create a node that has curvature on either side. This allows you to create smooth curves between multiple nodes.

Color Picker Tool(O): Makes the primary color the color of the area on the layer that you click. If the area is transparent the color will become black.

Measure Tool(Shift+M): Lets you measure an angle or distance by clicking and dragging.

Move Tool(M): Lets you move around a layer or selection by clicking and dragging. If you click on any part of the image it will select the layer that is highest up and is not transparent where you clicked, be careful with this.

Crop Tool(Shift+C): Lets you define an area of the image to crop the image to.

Rotate Tool(Shift+R): Lets you rotate a layer or selection by any degree.

Scale Tool(Shift+S): Lets you resize a layer or selection.

Flip Tool(Shift+F): Lets you vertically or horizontally flip a selection or layer.

Text Tool(T): Lets you add text to the image. Text will become its own layer.

Bucket Fill Tool(Shift+B): Fills an area of similar color within a threshold with your primary color.

Gradient Tool(G): Allows you to create gradients of different shapes and patterns on a layer.

Paintbrush Tool(P): Allows you to draw freehand.

Eraser Tool(Shift+E): Allows you to erase anything on a layer.


Color


Selecting and changing your color in GIMP is very similar to how it works in Illustrator and other image editing programs. Your primary color is the color on the top-left, your secondary color is on the bottom-right.

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Clicking the arrows in the top-right will switch your primary and secondary colors. Clicking on either your primary color or secondary color will allow you to change it and bring up the color changer.

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You can pick a new color either by selecting one in the color picker, changing the hue value, entering the RGB notation or entering the hex notation. The eyedropper and screen icon on the right will allow you to select a color from anywhere within GIMP, including the window itself. The buttons above the color picker will show different color selecting options such as a pallette, wheel, and CMYK values.

You can also save specific colors to use later by clicking the arrow button above “reset.” You can save up to 12 colors and select to use any of them whenever you wish. The reset button will change the color back to what it was before you started changing it.

The colors menu provides many tools for changing the colors of a selection or layer. Many of the tools are self-explanatory. The tools that I personally use the most and find most useful are Brightness-Contrst, Hue-Saturation, Exposure, Invert, and Colorize. You can learn how most of these work just by messing around with them for a few seconds.

Under the Edit tools menu you can fill a selection or layer with your primary or secondary color


Layers


I have mentioned layers multiple times in this guide, so now I will finally explain in detail how they work.

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A new layer shows any content it contains on a higher z-index than the lower layers. This allows you to have overlapping images and be able to easily define which one should be showed above others. Clicking the eye will toggle whether a layer is visible or not.

Layers come with their own tools which allow you to easily change how your image looks and how layers interact with each other.

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The first icon, the paper with the plus icon, in the layer options tray, seen above, allows you to create a new layer. By default it will make a new layer above the currently selected layer. The folder icon allows you to organize your layers into groups which will make sorting through your layers easier. This doesn’t tend to be an issue unless you are creating a very detailed and complex image which may require dozens of layers or you have a habit of separating every individual part of an image. The two arrow icons let you move a layer up or down, respectively.

The 5th icon is the duplicate tool, it will create a duplicate of the currently selected layer and will put the duplicate layer above the currently selected one. The anchor icon will anchor a floating selection, which is created when you paste something into a layer, to the current layer, this can also be done by deselecting the floating selection. So if you paste an image into a layer it will become part of the layer by clicking the anchor button. While it is unanchored you can move, rotate and edit it as you would with any layer. The mask tool allows you to add a mask to a layer. I personally don’t have much experience with this but if you want to get into complicated or professional image editing you should learn how this works. It will basically selectively modify the transparency of the selected layer. The last button is the layer delete button which will remove the selected layer.

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The layers dock header, seen above, allows you to change the opacity of the layer as a whole. This is different than layer masking as it won’t selectively change the transparency, it will just change the overall transparency. The modes changes how a layer interacts with the others. For example, you can make a layer act as an eraser for any layer below it, invert the layer colors, etc.

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The Layer tools also include a few more that are not shown in the layers dock. The tools that I find most useful that are only available here are:

Scale Layer: Allows you to scale a layer by dragging the corners in or defining the dimensions.

Crop to Content: Automatically resizes the layer to the size of the content it contains.

Layer to Image Size: Resizes the layer to be the size and position of the whole image canvas.

Right clicking on any visible layer will provide you with even more tools including Flatten Image and Merge Visible Layers. Flatten Image will combine every layer into one. I avoid using this one as it doesn’t respect transparent areas too well. Instead, I prefer to use Merge Visible Layers which will respect transparency and combine all visible layers into one. It should be noted that you don’t have to merge layers in order to save the image in .png, .jpeg or other image files, your image will automatically flatten(and respect transparency). If you are saving your image as a project file it is important to keep layers separated unless you are absolutely sure you are done editing them separately because layer merging cannot be undone if you close the program.

Additonally, you can crop the entire image, merge visible layers, and scale the image under the Image tool menu.


Paths


As highlighted above, the paths tool allows you to draw free-form shapes using straight or arced lines. This can prove to be very useful when designing shapes or logos. A path is created by connecting a bunch of nodes together to create a shape. Clicking with the path tool selected will create a node with no curvature applied to it, so any curvature applied to the lines it is connected to comes from the nodes it is attached to. Clicking and dragging will create a node with curvature where you originally clicked, the distance you draw determines the length of the curvature arms. The curvature arms can have their length and direction changed after.

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The node on the left has curvature arms which affects the path to the connecting nodes. The curvature arm going to the top-left affects the path to the node on the right which is why the path curves up and to the left.

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The node above is a node without any curvature applied to it which is why it lacks any curvature arms. The node has a square on it which indicated it is the selected node. If a node with curvature is selected the curvature arms will be visible like in the first image above.

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Pressing Enter, or the “Selection from Path” button in the tool options menu, will connect the last and first nodes with a selection which can then be changed and edited like any other selection. Pressing the “Fill Path” button will fill the selected region created by the path with your primary color. The “Stroke Path” option will draw a line along the path you created and this line can use any of the paintbrush options. Please note that Stroke Path won’t draw along any selection lines created by the path, so in the image above it would only draw along the curve at the top and not the line at the bottom.


Filters and Add-Ons


There are plenty of filters and tools that GIMP provides to you, but you can also add in your own or ones that other people created to allow you even greater. The filters it provides offer a wide range of deformations, enhancements, etc. Blur is probably the group of filters you will use the most, it includes Gaussian Blur, Motion Blur, Pixelation Blur and more.

As you might have noticed, there are two interesting sections at the bottom of the filters menu called Python-Fu and Script-Fu. These allow you to execute custom scripts to edit your image. Python-Fu is a built-in console which allows you to write code directly into GIMP which will then execute it.

Script-Fu allows you to execute pre-written code meant for GIMP which is where it differs from Python-Fu.

To add plugins, or add-ons, to GIMP, you have to find one online(or create your own) and add it to the GIMP directory which will then implement it as a tool that you can use whenever you use GIMP from that point forward. If you install an add-on while GIMP is running you will have to restart GIMP for the add-on to become live. One of the more useful add-ons, specifically for images that would be uploaded to Roblox, is Quenty’s Bleed Colors into Transparent Areas which I would strongly encourage you read how it works. His guide includes a step-by-step tutorial on how to install it into GIMP which is the same way you would install add-ons and plugins.


Miscellaneous


Right-clicking on an image also brings up a menu which contains most of the tools listed above.

You can edit keyboard shortcuts under Edit > Keyboard Shortcuts to make your experience better.

Dragging the rulers over the image allow you to create guides which can then be hidden/shown under View > Show Guides.

At the bottom of the image you can see the file size for the project. Additionally clicking on where it says “px” will show you a list of other measurements that you can use to measure the image such as inches and centimeters.

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When you change the canvas size you can center everything or drag it around to be positioned anywhere. You can also change any new transparent areas to be filled with your primary/seconday color, white or a pattern.

Clicking the chain next to any resize dimensions will determine if it keeps its aspect ratio or not. When the chain is solid it will keep the aspect ratio and scale properly, when the chain is broken it won’t keep the aspect ratio and the height and width will scale/resize separately.

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Closing


Hopefully you found this tutorial to be quite informative and helpful. I surely wouldn’t consider myself an expert with GIMP, but I know enough to be able to use it and explain to other people how to get started with it. If you have any questions feel free to message me and I will probably have the time to respond. I guess I should also plug my Twitter which I never post any graphic design on oddly enough.


Thank you for reading!

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Really great tutorial man.

and yeah something tells me that the type of person to have bittorrent isn’t the type of person to be using gimp :thinking:

Capturelol

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Seems pretty neat. I will give it a try.

Looks cool. Will try this myself.

1 Like