26 March 2009

Will it scale?

Posters are big. That's why they’re posters, not pages.

This means that posters generally are not WYSIWYG. No matter how you set your computer monitor, you can’t really see how your poster going to look full size on the paper until it’s printed. (An exception might be if you’re making your poster by tiling together a series of smaller, individual pages.) This is an issue that PowerPoint presenters never have to deal with – they can see on their screen if the graphics are coming up short.

If you have any graphics in your poster at all, this can be a problem. Graphics that look fine on the computer screen can look really bad when printed full size, if you’re not careful. This can be avoided if you understand the two basic kinds of graphics out there.

Vector graphics (top) describe shapes mathematically. Because the underlying equation for a square or circle or line never changes, as you increase the size, the image is displayed at the best resolution the printer or screen is capable of. Probably the best known vector format is *.wmf or *.emf.

Bitmap graphics (below) create images from many small, square pixels. This means that as you zoom in or enlarge, eventually you will hit the point where you start to see jagged edges. This is why high pixel numbers are one of the desirable features that people look for when buying a digital camera. There are many different bitmap file formats, but the best know are *.jpg, *.gif, *.png, and *.tif.

Currently, pixel based graphics rule the roost, thanks to the web and digital cameras. Search Google Images for anything, and you will find images made from pixels. Although there is a recommended format for vector graphics on the web, it’s very hard to find any examples on the web.

Many people make the mistake of taking a low-resolution bitmap image from a website – commonly a university or company logo – then put it on a poster and print it at several hundred times the size it was intended for display it. The results are invariably horrible, jagged images.

If you’re likely to be doing poster presentations routinely, you should invest in a graphics package that can create and edit vector-based images. Unfortunately, these tend to be the more high-end, specialty programs like Adobe Illustrator and CorelDRAW!. But the results are worth it.

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