Raster or Vector Graphics
Michelle Reed, Graphic Designer, Majestik Creations

Most clients typically have no clue what the difference is between web-use images and 
print-use images. They don't understand what it means to have images in RGB or CMYK, 
72dpi or 300 dpi, raster or vector.  I don't expect them to know the difference, but 
it is important to learn. So I have written this article to help you learn the difference.

When working with graphics, there are two ways to create them. Photos and other images 
saved as .jpg, .gif, .png, .bmp, are all called "rasterized" images. Those are generally 
worked with in the Photoshop, Paint, Printshop Pro, etc programs. Those are your standard 
"web graphics". The difference between .gif and .png is similar, they can both save an 
image with transparency, but I believe the .png file is more Web friendly and utilizes 
compression better (dithering). Monitors now have 32 bit and 64bit color, that is like 
your computer being able to have 32 million and 64 million colors to view on your screen. 
You can view lower resolution images on your monitor because of the ability to produce 
high color amounts.  

Now, here is where it gets interesting.... Files, such as .eps or .tiff are usually created 
in programs such as Adobe Illustrator, Quark and Corel Draw. These type of images are called 
"Vector" images. The difference between vector and raster is mostly for commercial printer 
usage. That is why they ask for those .eps files and here is why.

In a vector image, you can expand the file to an unlimited size without losing any of the 
quality. Picture this.... have you ever taken an image or photo on your computer and zoomed 
in on it like 200-300-400 %? It gets pretty fuzzy and distorted doesn't it? That is the copy 
being rasterized or pixilated. In a vectorized image, you can zoom in, expand, shrink, the 
image as much or as little as you want and it's edges and quality remain the same. Using these 
types of images, you are limited in your colors because of the CMYK ink that would be used.  
The vector graphics are the "flat" images that you see, there isn't much visual shading or 
gradation as would be with raster images. It can be done, but it is much more difficult and costly.

The most important thing to remember when working with a graphic designer, when you send 
them images or photos to work with, it is imperitive that you send the highest resolution 
(150dpi or higher, 300dpi preferred) otherwise those images will not be of the best quality 
and there isn't a whole lot more that the designer can do to improve it.  

I hope you all get a better understand of how this works. Basically when you take an image 
to a commercial printer, they do request certain file types, but that is only because you 
can print a smiley face on a regular printer and it looks fine, but if you want to blow up 
that smiley face into a 6ft sign, it will have major choppy edges and look too distorted. 
Vector graphics will not do that. Hope this helps put things into perspective.