Perfect lines

You may have taken a photo with a digital camera which, at first, seemed sharply printed, but when enlarged seemed blurry and "mushy" in places. If so, you have stumbled across a fundamental problem of digital graphic processing: Pixel graphics can be shrunk almost arbitrarily, but they can only be enlarged to a certain degree: Where no more material is available in the original photo, the software must "add" pixels, but this only works to a limited extent, and the result is not like the original photo.

This problem can be solved using vector graphics. In Linux, you can use the Inkscape program [1] to create vector graphics yourself. However, starting to use this rather complex application is not very easy. In this article, I explain the first steps of using Inkscape.

Digital Resolution

Digital photos and graphics are not just a specific resolution, the point density, which is specified as the number of dots per inch (dpi), is also important. The higher the dpi, the finer and sharper the graphic. The combination of resolution and density determines the context in which an image file can be scaled. The higher the resolution and dpi number, the less a graphics program has to "invent" when projecting and the more the graphic can be scaled; 300 dpi is the basic requirement for high-quality printing.

Today, increasingly higher resolutions are easing the problem with digital photos; however, the same still applies to digital graphics. Think of a presentation that is supposed to run on a projector with 720p or 1080p resolution: Photos you want to incorporate there must offer at least full-HD resolution. The same applies to graphics; otherwise, you'll see only a mash of pixels.

Graphics as a Formula

Vector graphics work fundamentally differently than pixel graphics: A vector graphic virtually describes the construction of the image and the ratio of the individual picture elements to each other. A vector graphic instruction could therefore read that a black line at the bottom of the image is occupying the entire width. When representing the graphic, the display program interprets this information and then displays the line accordingly. The line therefore always appears neat and high resolution.

Because a vector graphic describes all elements in this way and also defines the relationship of objects to each other, a complete graphic can be portrayed using mathematical formulae. It scales easily – on a smartphone screen or a meter-wide projection screen.

The Beginning …

Inkscape, which, like Firefox, Gimp, or LibreOffice, is regarded as one of the crown jewels of free software, can be found in the repositories of all major distributions. If it has not already been set up during the system installation, you do this easily using the respective package management system; the corresponding package is almost always called inkscape. Then, you will find an entry for the vector graphics program – which you can use to get Inkscape on the screen – in the start menu of the respective desktop.

At first glance, the Inkscape interface very much resembles pixel graphics applications like Gimp. In fact, some tools in Inkscape have similar functions to their counterparts in other tools. Do not be fooled, however; creating vector graphics is quite different from working with pixel images.

The work area takes up the majority of the Inkscape window, shown as a white sheet. Rulers on the sides show its dimensions. At the top are a few other toolbars next to a classic quick-start bar. You can access all important tools via the toolbar on the left edge of the window, as well as the path tool and some helpers that conjure up prefabricated forms in the Inkscape graphics. Working with paths in the context of vector graphics is rudimentary – so take your time to understand the underlying principle.