Understanding File Formats
There are two types of drawing programs used when drawing on the computer: Vector and Raster. Clients need both types of graphics, but don’t run out and buy more software – let’s first understand the differences.
Vector
Vector images are made up of lines and curves with points. To simplify a very technical description, a vector graphic is made up of lines and points with information attached to them. For example: If you were to draw a circle, the drawing would be made up of a line with a curve (360 degrees), a beginning and end point, a specific size, an outline color for the line, and the “fill”, or the color inside the line.
What makes vector images popular among graphic designers, printing companies, and other people who work with images is the fact that vector images are scalable – they can be easily made larger or smaller without losing any image quality. When you change the size of the image, the software simply redraws the design in the new size.
Professional designers also create vector images using “layers” – a feature which allows designers to isolate each element of the design in its own space. When all of the layers are shown together, the entire graphic looks like one image. Using layers makes it easier to change vector designs at any time – any designer can take a vector image file and look at individual layers to change the colors, fonts, or layout of a design. This is useful for an image that will be used with different media – a logo printed on a brochure can be more detailed and smaller than a logo sewn on a hat.
File formats: .ai .fh .cdr
Common Programs: Adobe Illustrator, FreeHand, CorelDraw
Raster
Raster files are images made up of square dots, called pixels. Each flat dot can be a different color in your picture. When you look at the dots from far away, they blend together and produce beautiful images, but when you zoom in, you can see the pixels.
What makes Raster images different is that when you want to make a picture larger or smaller, the resolution quality goes down. When you enlarge an image, the edges of the elements in the image look boxy and bumpy because the computer has no idea what to put in between the pixels that are there, or how to smooth them out. When you shrink an image, the computer has to just throw away random pixels. The pixels themselves can’t be made smaller, so the image just needs to have fewer of them.
All of this might make using raster graphic sound inferior, but they actually have specific uses that make them better than vector images:
- Internet: Raster files are smaller, so websites download faster.
- Photographs: Digital Photos are always raster images, and they are easy to take and edit.
- Clipart: You can insert raster images into a document or presentation in seconds.
- Screen resolution: The resolution of computer monitors are all the same, so raster images always look good.
File formats: .bmp .gif .jpg .png .tiff .pict .psd
Common Programs: Adobe Photoshop, Adobe Fireworks
So Which One Do You Use?
When you deliver a logo or a graphic design to a client, always deliver both formats. Customers will ask for “source files”, which mean files that can be edited and changed. A client may need vector files for printing, but raster for a posting on a website. Experienced designers have figured out an easy way to provide both types of files – design the original graphic using a vector design program, and then create a variety of vector and raster-based versions of the files from it. For example, using Adobe Illustrator it is easy to design a vector logo, select “Save As” and then choose both vector and raster-type files formats required by the client.
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