Done using GIMP 2.8 on Kubuntu Linux 18.04 LTS
To wrap up our tour of the tools, we need to look at a few of the tools that don’t fit neatly into any of the other groups we have covered, such as Selection Tools, Paint Tools, Transform Tools, and Color Tools, all of which we looked at in earlier posts. But that leaves us with a few more that are a grab bag of miscellaneous tools:
- Paths Tool
- Zoom Tool
- Measure Tool
- Text Tool
- GEGL Operation Tool
These don’t necessarily have anything to do with each other, but they are important so we should want to take a brief look at them.
Again, practice makes perfect, so you should open up GIMP and either create a blank image or open a photo to work with these tools. All but the GEGL Operation Tool have icons in the Toolbox, and all of them are accessible on the Tools menu.
To begin with, the Paths tool lets you create and manipulate Bézier Curves on your image. You can click on the Icon in the Toolbox, and this one does not have a pop-up dialog box like many of the other tools. Instead, you go to the Right sidebar, and on the top there is a section we’ll use a lot more often when we get to Layers. The first tab is Layers, the second is Channels, and the third is Paths, so you should open that when working with the Paths tool. Of course, there is also a Tool Options area on the bottom Left sidebar, just as with all other tools.
Bézier Curves are defined by anchor points and tangent lines, and you can manipulate the curve by moving the anchor points, twisting the tangent lines, or both. For example, if you select the Paths tool, then select Design Mode in the Tool Options and click on the image, you will get one anchor point. Click again on a different part, and you will get a second anchor point with a straight line connecting the two anchor points. This all works the same as the Selection Tools we looked at earlier. One of those points is active, the one you most recently clicked on, and that is the one that is an “empty” circle instead of a solid dot. From there you will have a tangent line with squares on either end. You can then adjust the curve by moving one of those squares to reshape your curve. Note that if you check the Polygonal box in the Tool Options on the lower left, you will get straight line segments between the Anchor points, which makes it very similar to the free form select tool. But the real power of this tool is curves, and this is a good option if you want to mix curved sections and straight line sections. When you get to the end you need to Control+Click on the very first anchor point to connect it to the last anchor point. This is a great tool for cutting out an object from one image to then use in another image.
You fine tune your path using Edit mode. This lets you add anchor points in the middle of your path, for instance, and you enter Edit mode by using the Control key as you click if you don’t want to keep changing modes. Used with other tools, like the Zoom Tool, this can let you draw very precise outlines around objects in a photo. If you then click Selection from Path in the Options on the lower left, you can do anything you want with it, such as copy the selection and insert it into another image. This makes the Paths tool extremely useful.
Paths can be saved as well. To do this, right-click on the path in the upper-right section, and select “Export”. Save it as an *.svg file, and you can then open it in another image (via Import), but also in another program. SVG stands for Scalable Vector Graphics, and that is the type of graphic that can be re-scaled without any problems because it is not raster based, but instead based in equations. So you could open this path in Inkscape, for instance, which is the premier open source Vector Graphics program, and you can also import from Inkscape. GIMP’s vector graphics tools are not all that powerful, but it is handy.
Finally, the Paths Tool allows you to do other things as well. You can paint along a path, you can stroke the path (which means drawing a line, which can be dotted, dashed, etc.), and you can even write text that follows a path. So you see this tool is really very useful.
This one is pretty straightforward. You can Zoom In, or Zoom Out. But it is very useful for making precise edits since you can zoom in to the point that you can see individual pixels, which can be very helpful in making a selection, whether you are using the Selection Tools discussed previously or the Paths tool discussed above. Note that you can also control the zoom level very precisely using the percent zoom setting in the Status Bar on the bottom:
This will let you type in a percentage for the zoom. When the image is at 100% it is no zoom at all, less than that is zoomed out, and higher numbers are zoomed in. And the crop-down lets you pick from some pre-selected zoom levels.
This lets you measure the distance in pixels between any two points, and the angle of the line connecting them. To use this tool, click on the first point, and holding the mouse button, drag the cursor to the second point. On the image you will see the line connecting the and an angle marker, but the actual data is on the Status Bar at the bottom, right next to the Zoom indicator:
The first number is the actual distance, computed using the Pythagorean Theorem (and I checked, it is accurate), the second is the angle away from the horizontal, and the numbers in parentheses are the horizontal and vertical displacements between the two points.
This is mostly standard if you have ever used a text tool in any graphics program, such as Libre Office Impress. You draw a box, and start typing in text. When you draw the box, a window pops up where you can select Font, size, and so on. I assume most people have seen something of the sort before, and this is very standard. But there are a couple of things to point out that you may not have encountered before. The first is Hinting, which is a technique for making fonts more legible at smaller sizes. There is a full discussion about it on Wikipedia (https://en.wikipedia.org/wiki/Font_hinting) if you want to get into the weeds, but for most people the idea of making small sizes more legible is sufficient. The other is Anti-aliasing, which is used in computer graphics to reduce the “jagged edges” that can appear, particularly when something is scaled up. There is a nice brief definition at Webopedia (https://www.webopedia.com/TERM/A/antialiasing.html).
GEGL Operation Tool
GEGL stands for Generic Graphics Library, and was introduced in GIMP 2.6. It is continuing to be developed, but as of GIMP 2.8 it was still not quite ready for normal use. The documentation carries this warning:
GEGL is in a very early phase and still under construction. The GEGL Operation tool is experimental.https://docs.gimp.org/2.8/en/gimp-tool-gegl.html
However, if you look at the documentation for GIMP 2.10, which is the most current version as I write this, you see instead:
GIMP-2.10 is nearly fully ported to GEGL. You will find here some operations that still are experimental.https://docs.gimp.org/2.10/en/gimp-tool-gegl.html
So, you can see from this that GIMP is developing this and making it central to GIMP’s further development. And there is a nice YouTube video explaining how GEGL is the future of GIMP. It supports high-bit-depth images and non-destructive editing, for instance, and beginning in GIMP 2.10 the GEGL filters will be replacing the filters GIMP had previously.
To use this tool, go to the Tools menu, and select GEGL Operation, and you will get this dialog box:
To pick an operation, click the drop down and make a choice. There have to be 50 or so choices here, and many of them are not immediately clear to me, but some of them are Newsprint, Gaussian Blur, and so on. For each tool, a settings dialog will open. Remember to keep Preview checked so you can see what your changes are doing, and remember that the Reset button will always get you back to your starting point.
Because GEGL is where GIMP is going, I have chosen to support the principal developer, Øyvind Kolås, through his Patreon account. As you may know, I advocate supporting Free Software, and since I am using this wonderful program I intend to help make it better through my financial contributions. And while GEGL is not 100% there yet, it is exciting to see where it can go.
This does finally complete our look at all of the tools available in GIMP. Again, open an image and practice using these tools to get familiar with them.
Listen to the audio version of this post on Hacker Public Radio!