GIMP (short for GNU Image Manipulation Program) is an awesome image editing tool and it is the one preferred by many of the more experienced image editors on the Wiki. It is also completely free, unlike PhotoShop, so you don't have to shell out anything to become an image guru on the wiki. If you don't have it already, I highly recommend downloading it.
This page is meant to be a comprehensive guide on each of the tools and options available as well as when it is appropriate to use them and when it's more appropriate to use something else. It may be long, but it is intricate and is actually fairly brief for a complete overview. This guide was written using GIMP 2.8.4.
I won't be providing a guide on basic transparency or translucency because those two topics are covered already by Spineweilder and Fergie, respectively. In fact, the latter part of this guide is written with the assumption that you already know how to apply simple transparency and simple translucency. If you do not already know, I suggest you stop reading this page after the creating your own tools section and then take a look at those guides as well as doing a little bit of practice. I will, however be providing tips with the tools that can help speed up and clean up those two processes as well as guides on doing transparency
half-assedly faster. The lazy trans section is not applicable to every image, though, and you should actually know how to do it normally.
If you are interested, the full and official documentation exists here.
- Guides by other users
First let's get to know each tool. Every tool has a use somewhere, but I will only be exploring the tools that have an appropriate use on Wiki images with any real detail.
||Selects an area for editing with a simple rectangle. The dimensions and location can still be edited after the initial selection by playing around with the squares on the corners of the selection box and the rectangles on the edges in the middle. You should only use this tool for cropping and even then, only for images that won't have transparency upon upload.
||Similar to the rectangle select tool, but with circular selections. You will rarely use this tool, but I've used it for translucency on images like File:Nyriki's portal.png.
||This is the tool for transparency and translucency. It is affectionately called lasso around here. It draws a series of lines that, when finally closed, define your selection area. You can also draw out shapes freehand but this is usually sloppier unless you have superhuman dexterity. You will almost always want to use this tool. When in doubt, use the lasso.
||An extremely underrated tool that selects connected areas of similar color. Fergie has stated she will murder anyone who uses this for translucency, but the fact of the matter is: this tool is really useful for translucency because semi-trans is done by sections of similar color.
||Shift + O
||Selects all regions in the image by looking at their colors. Similar to fuzzy select, but the areas do not need to be connected for them to be included in the selection. You should rarely use this tool unless you want to be doing lazy inventory icon trans.
||Selects areas by their edges "intelligently". This is a ballsy tool to attempt to use. You honestly should not even try; you'll spend more time trying to get decent selections with this than if you had just used the lasso.
||Selects foreground objects. Irrelevant—images on the wiki should only be one layer. You should never use this tool here.
||Create cubic Bézier curves. Click two endpoints to define a straight segment; drag the middle to make control points visible; then drag control points to fine-tune the curve. Once created, make the curve(s) visible (Edit→Stroke path…) or (if paths define a closed space) use that as a selection for further edits (Select→From Path).
||Selects the exact color of the pixel it's on for you to use. This is one of your best friends for translucency.
||Zooms in and out. Not that useful as there are keyboard and mouse shortcuts for you to use.
||Shift + M
||It measures stuff in your images. Unless you're a nerd who likes these kinds of statistics, you won't be needing this tool.
||It moves stuff. Since we only work on a single image for files here and because we keep them as pristine as possible, you generally won't be needing this tool.
||It aligns stuff. Allegedly. You won't be using this.
||Shift + C
||It crops stuff. There are easier, faster, and more efficient ways to crop in most cases, but this a good tool for the initial crop of a raw printscreen.
||Shift + R
||It rotates stuff. Good for... um... rotating stuff!
||Shift + T
||Allows you to resize a selection. As we like our images as big as possible, you will never use this. Do not attempt to make an image bigger, as that will only make it look fat and weird.
||Shift + S
||This tool is just plain nuts. Don't use it.
||Shift + P
||This tool changes the perspective of the selection. Don't use it.
||Shift + F
||Flips the selection vertically and/or horizontally. You will rarely need it, but sometimes you come across an image facing a way you don't like.
||Shift + G
||Let's you mess up a selection in soooooooooooo many different ways. Never use this tool.
||Allows you to add text to the image. Unless you are active in creating maps for imagemapping, you will not need this tool.
||Shift + B
||Fills an area with a color as well as an eclectic selection of options. One of your best friends for translucency, especially when paired with the color dropper. It can also be used for inventory icon transparency. You will only really use this tool on the normal and color erase settings.
||Does blending and gradients that fill the entire image. You won't ever use this tool.
||Used for drawing and stuff. You won't really use this.
||Also used for drawing and stuff, but, unlike the pencil, this one isn't a completely solid shape (but it can be). Since you can use this brush with varying hardness, it is great for doing particle translucency.
||Shift + E
||Erases an area of its colors. It can be useful for that, but, frankly, the bucket fill tool set to color erase is more useful to prevent any overlapping. The difference is that the eraser knows no bounds, removing colors regardless of value; the paint bucket on erase can have its threshold changed. What makes it worthwhile is that it is the only tool that has anti-erase (adds color back to the transparent area) which can prove useful if you ever need part of the background back.
||Used for vandalizing your local restaurant's brick wall. Very fun there, but also useful for recreating particles.
||"Calligraphy-style painting". What...? You won't be using this tool.
||Copies a selection for cloning and probing. The source area is selected by left-clicking while holding CTRL. Good for more advanced image clean up; however, it requires much more discretion and care to keep the image pristine. I used it to remove the player character from File:The Faraway Place where Things are Kept.png.
||Useful when combined with the "Clone" tool to clean up patched areas. The source area is selected by left-clicking while holding CTRL.
||The hideous offspring of the "Perspective" and "Clone" tools. Don't use this tool.
||Shift + U
||Blurs/Sharpens the images. This tool actually proves useful for cleaning up the staircasey edges that result from applying translucency. You will have to be careful, though, because too much blur can make the image look odd. Sharpen is fairly useless as an undo for blur because it usually adds colors that you never saw there before.
||Smudges the colors of an image to follow your brush. Another useful translucency clean up tool. Use it after selecting a wall to push colors into to prevent any mistakes.
||Shift + D
||Darkens or lightens the area under your brush. Have fun finding a legitimate use for this on the wiki.
Besides just the tools given to you on the interface, there are also tools that exist in the menus in the top nav bar. I'll try to explain the useful ones here:
- →Autocrop Image
- The tool for cropping after a trans. It will remove all the unnecessary areas of transparent pixels. Always use this after applying transparency.
- →Transparency → Add Alpha Channel
- Allows you to apply transparency. It is literally impossible to do trans without this being done at some point.
- →Transparency → Color to Alpha
- Removes a given color from the selected area by making it transparent. Perfect for particle transparency and transparency where there is detail to be kept (such as a ghost's face). It also exists under Colors → Color to Alpha
- Use this tool to turn an entire area white in preparation for translucency by maxing out both brightness and contrast.
- →Toolbox - Tool Options & →Dockable Dialogs → Tool Options
- Opens the windows that have all your tools. You should always keep them open, but if you accidentally close them you can find them here.
Knowing what each tool does is a start, but all of the tools have additional options for editing with them. I will cover the important ones.
First thing to know: Those two boxes at the top are your foreground color (the one more to the left) and the background color (the one to the right). You can switch between them freely by clicking the arrow. These aren't part of the tool options.
The next option is the mode (which you will mostly be changing with the paint bucket). The only modes we care about are covered below.
The last four options are your brush options. You usually want a smallish brush size (around 15.0-20.0) and almost always want it to have it set to the circle brushes at either hardness 075 or hardness 100. You should keep the aspect ratio and angle at 0.0. These just change the specific shape of the brush and how rotated that shape is. Don't feel afraid to experiment with brush sizes and shapes though to find what is most effective.
Opacity is how much alpha the coloring will have (or subtract if you are using a color eraser). Generally, you want to keep this to 100% for coloring. For translucency use varying amounts all while trying to get it as close to the original opacity as possible.
Some of the Modes you might actually want to use:
- Use this to color plain, untextured areas when doing translucency. Use it with the paintbrush tool when recreating particles/
- Color erase
- Use this with a lower opacity to get as close to the correct amount of transl as you can. You can also use it to erase stuff... I guess....
- If you know how to add and subtract colors, this is helpful for doing the maths.
- Additions & Subtract
- These are the most helpful tools in getting your colors on a translucency perfect. You'll only need them if you're using color to alpha to remove a background and afterwards the colors are incorrect; e.g. the area is white, but after removing the green it appears purple.
The tool options for selection tools are fairly simple. There are four modes: replace, add, subtract, overlap. Replace changes the selection to just what you have recently selected. Add and subtract keep your original selection for the most part, but add to or remove from it, respectively. Overlap makes you create a selection, and your new selection will be any areas that are in both the original selection and your new one.
Always have Antialising checked, or else. Use feathered edges when you need to have, well, feathered edges. Keeping the box for selecting transparent areas is usually a wise idea. Remember that you need to have these options checked before you start outlining a selection for them to take effect.
Threshold (which also exists on other tools such as the paint bucket) is an important option to understand. It defines how to select what is included based on a given pixel's attributes. The slider is how wide of a range to include where 0.0 is only matching the current pixel exactly and 255.0 is everything. The mode under this is what will be looked at for the inclusion. Composite looks at the color as a whole and the other options look at only their given attribute.
The Blur / Sharpen and Smudge tools both have the rate slider. This is basically how blurry it will be or how strongly it will smudge where 0.0 is almost nothing and 100.0 is a whole lot. The Blur / Sharpen tool also has two methods of convolving; smudge does not have these options. The blur option is the only one you will want to use. It does color blending where as sharpen does color segregating. The sharpening usually does not turn out very well.
There are a lot of useful keyboard shortcuts for you to use, but not all of them are useful for Wiki images. In addition to the tools' shortcuts above, here are some others you'll find useful:
- Control / Shift
Control and Shift provide a quick and temporary selection of different tool options on certain tools. Some general examples as well as specific, useful ones will be provided in the next section. There are also numerous keyboard and mouse shortcuts to be used with them.
- Control+S / Control+O
The shortcuts that exist everywhere. Control+S saves the image; however it does it as an xcf file, GIMP's native extension... Control+O opens a new file.
Exports the image to a given file extension. Shift allows you to choose file name. Usually, Control+E will overwrite the opened file.
- Control+C / Control+X / Control+V
The other shortcuts that exist everywhere. Copy / Cut / Paste
Inverts selected areas. You'll use this a lot when doing transparencies.
Don't worry Gob! Just Control+Z!
- Control+Z / Control+Y
Undo last action and redo last undone action, respectively. Extremely useful, especially if you make a lot of mistakes. And because you are not Mol, you will make a lot of mistakes.
Control+W closes the current file you're working on. Control+Shift+W closes all the files.
Control+A selects everything. Control+Shift+A makes you deselect everything.
Repeats the last filter you've used. Holding shift will reopen the window for the last filter to allow you to change the options. If there is no input for the filter (e.g. Autocrop Image), the filter will simply be repeated. Examples of filters you'll use are Autocrop Image and Color to Alpha.
Deletes the selected area completely. Similar to Control+X, but it doesn't save the selection to your clipboard.
- Zooms in and out. Pushing the wheel forward from you zooms in, pulling it backwards zooms you out.
- Allows you to pan. The wheel by itself allows vertical panning. Forward moves it up and backward moves it down. Holding shift changes it to horizontal panning. Forward moves it left and backwards moves it right.
- Clicking the wheel and holding it allows for free panning around the image by moving the mouse. No buttons modify this action; e.g. holding shift and clicking still results in regular panning.
- For any tool that has a brush, holding control+shift and moving it forward or backwards will allow you to scroll through the brush shapes.
Here are some useful shortcuts for using Control and Shift with certain classes of tools. Hints are also given by GIMP on the bottom of the image editing window.
- Selection Tools
Shift and control allow you to change the boundaries of your selection and even select multiple areas that are not connected all while keeping your original selection. They only need to be held on the initial click of the tool. This means you can reformat your selections or continue selecting points with the lasso tool without having to hold the key. Shift adds on to your selection. Control deselects the area from your selection.
- Color dropper
Holding control will simply make the dropper change the background color. Holding shift will give you an awesome little menu box that gives you information about the color you've selected. The RGB and HEX color values should prove useful for eyeballing colors as you apply semi-transparency. Knowing exactly how transparent the pixel is (the alpha statistic) will allow you to make cleaner, more consistent translucencies.
- Paint tools
Shift and control have interesting properties on these tools. Holding control simply switches to the color dropper tool for color selection. Shift, on the other hand, creates a line from where you last clicked to where you click next while holding shift and acts as if you swiped your brush along that line. Here's an example using color erase:
Control is sorta boring here, like the paint tools, it just switches to the color dropper but instead to change the background color. Shift allows you to create a line to swipe your brush across like the paint tools. Alt is the most interesting option that eraser has; it gives you the ability to anti-erase. Basically, this just does the opposite of erasing it; i.e. it moves the color out of the alpha layer making it visible again. This is useful if you've made a small mistake in your boundaries for a transparency or if there is not enough background available for you to use for translucency.
- Bucket fill
Control switches between using the foreground color and the background color for fills. Shift fills the entire selection regardless of your threshold.
Control only does something for blur – it changes the effect between blurring and sharpening. Shift does the same thing with these tools as it does with the paint tools; i.e. it makes a line across which it will swipe the brush.
Of course, all those shortcuts are simply the default ones provided by GIMP. You can actually create your own shortcuts, including rewriting the default ones. It's fairly simple as well.
- Go to the edit menu and find the preferences dialog (Edit→Preferences).
- Click the Interface menu item on the left-hand side. In the menu on the right, find the Configure Keyboard Shortcuts button
- In the dialog that opens up, just find the action you'd like to change or make a shortcut for and click its name then make your desired keystrokes.
Make sure the Save keyboard shortcuts on exit box is checked, and the moment you close that window, the shortcuts you created will be in effect and ready to use.
There are plenty of methods for applying transparency. While lazy transing allows you to apply it faster, it is still effective and you still have to clean up after any messes you made. Only inventory icon transparency is foolproof. Using a lazy trans is also not excuse for sucking.
Select by color only really finds its use for removing inventory shadows. First, you should use fuzzy select to remove the blue areas from the icon. Here's an icon that had its blue area selected with fuzzy select on a threshold of 15.0.
Use the delete button to remove the selected blue area from the image. After that, you should choose the select by color tool and move the threshold slider all the way to the left, setting it to 0.0. Find any one of the brown shadow pixels and select it. All of the brown shadow pixels should now be selected, like so:
Simply press the delete button again to remove the shadow, autocrop the image and then save it. You're done and have a ready for display image.
Semi-transing chat head necks isn't necessary, but what the hell?! It makes them look nicer and makes people think you're a real go-getter!
Chat head semi-trans can be done fairly easily with the use of fuzzy select. Step one is to apply normal transparency around the chat head. After that (or if this was already done in a previous upload) choose your fuzzy select tool and put your threshold to around 15.0. You may or may not have to fiddle with this or use the lasso to deselect certain areas, especially if the subject has darker skin or a dark colored beard. If your subject has very dark skin, you are better off using the lasso. Your selection should look sorta like this:
Find some point lower on the subject's neck to get their true skin color with the color dropper; don't use the color dropper on any part of the neck that will be getting trans. Use the Brightness-Contrast settings to make your selection white and then use your paint bucket to color the area to the subject's skin color. Finally, change your settings on the paint bucket to 'Color erase' and then change the opacity to around 60.0. Use the paint bucket on the neck to apply the semi-transparency. The process looks like this:
Repeat this process for the other neck. This time, however, you will notice some pixels between the selected area and the already trans'd part of the next that weren't selected with the fuzzy select tool. There are also some in between the selection and the solid neck. You will have to select these pixels individually. From there, the process is the same except you'll be using an opacity of about 20.0 on the color erase fill. Do not forget to change the fill type for your paint bucket back to Normal and the opacity back to 100.0 for coloring the neck.
You will notice that the edges are staircasey. To fix this, go to the Blur / Sharpen tool. Set the Convolve type to blur, the opacity to 100.0, the size to around 5.0, and the convolve rate to about 8.0. The brush's shape doesn't totally matter, but it is best to use the circle brush at either 075 or 100 hardness. Run the brush over the edges of your semi-trans'd areas and you should end up with a nice looking chat head like this that is ready for upload:
Sometimes, translucency can be done much more quickly with the fuzzy select tool. Sometimes, it's also more effective too. You must use your best judgement to assess whether or not you should allow yourself to be lazy on a transparency.
This image to the right is an initial selection for a semi-transparency on the lucky arcane spirit shield. Notice how all of the image is some shade of this brownish-yellow. Also notice how the image was taken on a fairly solid brown surface. This gives each of the sections a decent distinction in their yellow-y-ness. The selection I got there was a little difficult to get, but it worked. It was rather tedious, but with a threshold of 2.5, I managed to nitpick the exact section I wanted.
On the other hand, check out this image:
All of the areas that need semi-transparency on the image are about the same color and it is unique in color to the rest of the image. A higher threshold can be used without too much risk (I used 30.0 here). I got all of what I wanted (and only that) with just a few clicks of the fuzzy tool.
There are certainly images where you simply cannot use the fuzzy select tool effectively. Images like File:Fairy Queen.png where the background behind the translucent parts is too dynamic or like File:Magic stone detail.png where the colors are too similar.
Not every image can be semi-trans'd lazily. When in doubt: use your lasso.
This image is too blurry!
Clean up is very important. Regular transparencies will never require any additional editing to make the image presentable, but translucencies, on the other hand, almost always will. The same method that I explained earlier for how to clean up chat heads can be used here. Select your blur tool and have it on a small brush size (less than 10.0) and a low convolve rate (less than 10.0) at full opacity (100.0). The brush's shape doesn't totally matter, but it is best to use the circle brush at either 075 or 100 hardness. Run the brush along the edges of the semi-trans to blend colors on the edge and make the image not look like it was done in MS Paint. Always be careful. If an image is too blurred it detracts from its original integrity. Keep your images as clean and pristine as possible.
You should always use blur on semi-trans that is adjacent to solid parts of the image, but another moderately effective method for trans adjacent to trans is to use the lasso tool to select an area of edges to clean up. If the edge you are working on is the boundary of two semi-trans'd areas, your only option other than blur is to use the smudge tool and push the colors into one another. Keep your brush size fairly small (less than 15.0) and the smudge rate moderate (around 50.0) and have opacity at its max (100.0) You will still have to be slightly careful though. After pushing colors in from one side, invert your selection with Control+I and do it again from the other side.
You have one more option for cleaning up the edges that are next to the empty parts of the image. Doing so is exactly the same as applying regular transparency to an image; create a selection that outlines the subject, invert the selection, then delete. If it was already trans'd before your semi-trans though, you don't need to outline all of the image, just the edges of your semi-trans; the rest of the image can be left alone assuming the transparency was decent.
Making your files small
One of the most important things with files is their size. We want the image to be as big as possible (without being obscenely big, of course); in a similar respect, we want the file size to be as small as possible without any loss in quality.
When saving an image and/or exporting it to png, you should get this screen to the right. You'll be prompted to export if you either explicitly choose to export or if you attempt to use "Save as" and use a different file extension in the name you're trying to save as. When you see this window, you want to make sure that every option is deselected and that compression is set to 9. Save these preferences as your defaults so that you don't have to uncheck each box every time.
To dispel any possible rumors: Deselecting 'Save color values from transparent pixels' will not remove colors from semitransparent pixels; it will only remove it from 100% transparent pixels. These pixels do not need their values saved. Actually, saving them takes up a whole lot of extra data.
Simply saving the image again may not overwrite it with these options. To check this, close the window after you save it and then reopen it. Go to the eraser tool and hold alt to choose anti erase and swipe any part of the transparent area. If it is a solid black background, then no color values were saved and it worked; if not, try again. Double check that you did actually save these options as your default. I've also heard of problems with the defaults not loading every time. This is probably because you have an older version of GIMP (my best guess), in which case I suggest upgrading.
In either case, you should start using overwrite file or export to instead of save. Overwrite file automatically converts the file to its original type and uses your saved optimization options in a single click. Export to does the same thing, except you choose a file name. If your work space was created from your clipboard, then you will be forced to use export instead of overwrite file.
Exporting files with these options under the export option just once seems to fix the problem of them not loading every time.
Further compression can be done in PNGGauntlet. This is an awesome tool for making your files as extremely small as possible, but if you have all those options selected for your transparencies you should be fine. PNGGauntlet usually just decreases files to a size of about 95% after the export from GIMP. PNGGauntlet (or any other png compression tool) should be used for files that are still fairly large after trans or that won't ever be getting transparency (≈500 kB+). I highly recommend downloading PNGGauntlet, but if you promise to save those options shown above, I won't bug you about it.
Check out this image for how much smaller files can get: File:Runed sceptre detail.png.
- The first revision of the current image is by Coel. It has no compression stuff at all; it is 728 kB
- The next revision is by me, I compressed it with just PNGGauntlet; it is 651 kB
- The next revision is done on my bot, ɘ. All I did was save the file and then export it in GIMP with my saved defaults for optimization; it is 58 kB
- The most recent revision is a final push for compression with PNGGauntlet; it is 53 kB
Holy crap! That image is 7.28% of its original size and with absolutely no loss in visual quality. Also, ain't it funny that its optimal size is 7.28% of its initial size of 728 kB?
Not every image will experience such an awesome level of optimization as this one, though. Every bit (or should I say byte?) counts, though and it is best to have files as optimized as possible. The more transparent pixels there are on an image, the more you can cut off from its initial size.
GIMP also totes its own method of compressing animations. It exists in the Filters menu under Filters → Animation → Optimize. There are two options for optimizing: Difference and for GIF. Which one you use doesn't really matter; however, Difference usually makes the files slightly smaller than GIF but still not by much. The process does take some time, but it makes animations a lot smaller, and it's still relatively fast. When it is finished, it will open a new window for the optimized image from where you can export it over the old file. I'm not exactly sure what options are best for exporting to keep the file, but I believe the ones I have set here work well. Don't ever forget to save it as an animation.
Unfortunately, optimizing GIFs is a riskier process than PNG files; it isn't a guaranteed success. The success rate is likely dependent on the version of GIMP you have, and I assume that newer versions are less likely to fail. Under the Filters menu, there is an option to watch the animation (Filters → Animation → ►Playback…) I suggest watching the animation a few times and comparing it to make sure that it is definitely the same visually. If it is, then export it over the old file; if not, then either try again or give up. It's probably not worth your time to constantly try to compress a file.
Well, that's about it. Hopefully you learned a thing or two and hopefully you also want to take your image editing to a higher level. Whether that means actually editing an image for the first time ever or entering a new realm and making it your forte, you're off on a step in the right direction.
If you have any questions, comments, feedback, or things I've missed, feel free to tell me on my talk page.
That's all, folks!