Corporate Logo Blog

Computer generated graphics come in two flavours: raster images (also called bitmaps) and vector images. They both coexist because they are each required for different applications. It is quite easy to translate a vector graphic into a bitmap but quite tedious to generate a vector graphic from a bitmap.

So what are the advantages, and the reasons we need both?

Bitmaps are the only way we can represent photographs electronically. They are akin to those display panels you have seen made up of light globes arrayed in rows and columns. Seen from enough distance, the eye merges their luminescence into one single image. As each lamp is turned on or off virtually any image can be displayed.

In computer lingo those "lightglobes" are called pixels. If you stare close enough with a magnifying glass to a computer or TV LCD screen you will see them. For colour they can each be either red, green or blue with up to 256 levels of intensity. The human eye does a marvellous job of integrating all that stuff and seeing things which literally don't exist (like seeing yellow when only red and green are there...)

Sounds great - so what is the catch? Why do we need vector graphics as well? The catch my friend, is called the resolution - the number of pixels we have horizontally and vertically. For a typical laptop LCD display that might be something like 1280 by 800 pixels. So far so good. Now if we want to print a beautiful photograph on glossy paper the resolution might be 300 pixels per inch which means for an A4 size page that would translate to 3500 by 2480 pixels!

Our initial image is now only a third in size of what is required. Some smart operators have had the idea of approximating each pixel of the larger canvas but some ugly distortions appear - some sort of staircase effect alongside every oblique line or boundary. Now you've got it - bitmaps are great to represent photographs but they are tied to their intrinsic resolution. You can always shrink down a bitmap without ill-effect but you cannot magnify it without ugly artifacts.

Here comes the vector graphic to the rescue, but at what cost? Vector graphics are just a list of mathematical points representing lines, circles, rectangles, Bezier curves (quadratic equations) each with their own colour and thickness. Perfectly mathematical - computers love it, it can all be boiled down to a bunch of numbers... It can be drawn at any scale with perfect precision, blown up, shrunk down, rotated, flipped to its side, etc... the catch? It is impossible to represent a photograph that way. The best you can do is to have gradients of shades which look like some airbrushed artwork. It is easy to translate a vector graphic to a bitmap of the desired resolution. The other way round requires a lot of skill and is always a manual process. You will end up with a touched up illustration - not a photograph.

Back to the issue of logo artwork. By now you've figured out that your logo needs to be printed onto anything from a postage stamp size label to a delivery van size signwriting. Because logos are graphic symbols they are best represented as vector images to ensure they remain sharp and crisp no matter the size of what they are printed on. Your corporate image depends on it.

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