Illustrator Vector Graphics


When we create artwork using Adobe Illustrator we are creating vector-based shapes or graphics. This is geometry based on mathematical calculations and equations. Such lines, curves, anchor points and colours are generated in quite a different manner than the pixel-based imagery of programs like Adobe Photoshop, which are known as bitmap graphics.

The lines, curvature, width and points of Illustrator shapes have their dimensions and positions determined by mathematical computations. For example, a black circle on a white page in a bitmap program is produced by a series of thousands of pixels, each of which has a number for colour and brightness. This is known as a map of bits of digital information, or a a rectangular grid of pixels (a small square or dot of colour). Ultimately these numbers are created by the binary system of ones and zeros. This is why Photoshop images can be quite large in size, depending on the pixel width and height, together with the resolution of the image, which is the number of pixels per linear inch. The resultant string of code can be quite large, amounting to thousands or even millions of pixels.

In contract to this method of producing and recording imagery Illustrator would create the black circle on the white page with a few bits of code for the size of the page, a few bits to determine the colour of the page, some more for the position of the circle’s centre point (the x and y coordinates), radius and width, as well as colour. In total the resultant binary string may only amount to a few bits of code, hence the relatively small size of such vector files.

In addition whilst the resolution of a bitmap image will determine its quality, especially when scaled upwards, similar imagery produced in vector software is known as “resolution-independent” in that it can be scaled from anything like a postage stamp size to the size of a billboard without losing its quality, the reason being that the whole artwork is recalculated each time.

A pixel based image when scaled upwards tends to look “pixeleated”, meaning that the individual dots can be seen with the naked eye, tending towards a more blurry appearance. This never happens with vector graphics due to the recalculation of the mathematical definition of the imagery. It could possibly be concluded that vector images are much superior to bitmap based graphics, but it really depends on the nature of the graphics. For example, photographs are best defined as bitmaps, known as “continuous tone”, whereas diagrams and illustrations are best produced by vector graphics which will retain their solid lines and colour.

To expand this idea further, bitmap imagery may be imported into Illustrator and “vectorized” using the program’s Image Trace function. And similarly vector imagery may be “rasterized”, or converted into pixels, for example if such imagery were to be exported for web or screen.

And so neither type of program, bitmap or vector, is necessarily superior to the other; it is all a matter using the correct tool for a particular outcome. In summary the two types of program work hand in hand.

Tom Gillan has been training Adobe Illustrator to corporate clients in Sydney for seven years. You can learn more about Adobe Illustrator Courses when you visit this link.

Kizuna Yumeno
Image by Danny Choo
Here are the blueprints for Kizuna in her Solar Marine uniform – open the image in another tab to see it in full res. Feel free to use these for cosplay, illustration or inspiration.

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