Introducing Vector Graphics and Inkscape

Paths and objects can be combined very quickly with boolean operations, such as intersection, union, difference, exclusion and others. Simply select the objects to combine and choose the desired operation from the Path menu. Figures 3 and 4 show what you get when you intersect an oval and a star.

Figure 3. Intersection of a Vector Oval and a Vector Star

Figure 4. The Same Intersection with a Different Boolean Operation

Solid colors can be dull, don't you agree? The fact that vector drawings are generated through computer instructions doesn't mean that their components must all be in solid colors. To create smooth color transitions (that is, gradients) from one side of an object to another, select it and open the Fill and Stroke dialog from the Object menu. That window allows you to apply several gradient types and place the corresponding stops—the exact start and end points between which the color transition must take place. Gradients can be applied to any object, including text.

Inkscape has buttons or menu entries to copy, paste and duplicate objects. Sometimes, however, what you want is a clone. Inkscape clones are special copies of an object that can be moved around, scaled or rotated at will but remain linked to it. By this we mean that any change to the original is applied to all its clones automatically. If you press Shift-Alt-D, a clone is detached from its ancestor and becomes a fully independent object. Clones can be tiled (Edit→Tile) to create patterns with many kinds of symmetrical or pseudo-random layouts. Reflection, rotation, radial placement and row and column shifting are only a few of the available choices, as shown in Figure 5.

Figure 5. Fill and Stroke Applied to the Object on the Bottom of the Image

One great thing in Inkscape is its Undo History. Not only can you undo all the changes you have made to a file, but they also are displayed in a nested mode, as shown in Figure 6, which makes it much quicker to go back right to the point you wanted.

Figure 6. Comprehensive undo lets you get back to the exact operation you have in mind.

Inkscape can convert drawings or parts of drawings to PNG bitmaps. Select File→Export as Bitmap, and remember to choose the right resolution; the default is 90dpi. Besides its native SVG file format, Inkscape also can save your masterpieces in several special formats, including PovRay, LaTeX, encapsulated PostScript, Adobe Illustrator 8, AutoCAD Dxf and OpenDocument drawings.

On the opposite side—importing already-existing graphics—a really neat feature of Inkscape is the capability to generate drawings from LaTeX formulas. Most people, however, will find it much more useful to “trace” JPEG, PNG or GIF images—that is, to convert them to vectorial format. Some advanced Inkscape users even trace the bitmaps that they generated from original vector drawings. The reason for doing this is that the unavoidable degradation may be exactly what is missing to make your work look more realistic.

Normally, if the starting bitmap is simple, the traced version is pretty good. Tracing something as complex as a photograph is theoretically possible, but in practice, the process is often so complex that it greatly slows down Inkscape or simply halts it, depending on the computer. This said, there are many different ways to trace bitmaps with Inkscape. To try them, import a bitmap, select it and then click on Path→Trace Bitmap. In the tracing pane, you'll then be able to generate one or more vectorial paths, starting, for example, from the colors or the levels of brightness of the original image.