Often there is confusion between the distinction of vector graphics and bitmap images. Understanding the difference will help ensure the quality of your company’s visual materials in both print and web. 

I like to refer to a bitmap as being an image rather than a graphic. Even though the words “graphic” and “images” are considered interchangeable, I find that to be part of the confusion. A graphic is a computer generated drawing of an object, person or thing. An image, like a photograph, is a representation of a actual object, person or thing.

Bitmap images are made up of pixels in a grid. Each pixel contains specific color information used to create an image. They are an exact visual picture composed of exact information at a fixed size. This pixel goes here and is this color; that one goes there and is this color, and so on. A photograph, whether it was scanned in to your computer or taken by a digital camera, will always be bitmapped. There are thousands of different colors, shading and gradations in a single photograph. It must be composed of hundreds of thousands of individual pixels, too complex to be drawn as Vector Art.

The number of pixels in a bitmapped image determines its resolution: dpi (dots per inch) or ppi (pixels per inch). When printing them, the dpi should be at least 300 at 100% actual size. If you enlarge the original image, the computer will add additional pixels based on the surrounding pixels. Since there is no source for this additional information, the color values have to be estimated. This will cause the image to become blurry and jagged.

Pixels can not change size. It takes more pixels to fill a larger space and less to fill a smaller space. To make an existing bitmap image smaller, pixels are deleted and once that information is thrown away, it is gone for good (which is fine if you are using it for a smaller space). You can repeatedly make an image smaller and maintain the image quality needed for that space. But if you need to increase the size back... I hope you’ve saved the original image.

Vector graphics are quite the opposite. Instead of being a literal representation, they are mathematical creations consisting of points, lines and curves that can be freely manipulated to any size without losing information. The programs used to create them come with instructions on how the graphic is drawn. A vector graphic can be reduced in size to fit a business card and resized again to fit a billboard with no loss of quality. Because of its scaling flexibility, it’s a good idea to have your logo designed in a vector program. And always keep a copy of the original vector art! If you import your vector logo into a bitmap program, such as Adobe Photoshop, your logo will be converted to a bitmap image. There is no way to convert it back to a vector graphic. Once it’s converted to a bitmap, it stays that way.

Vector or bitmap, ALWAYS KEEP A COPY OF THE ORIGINAL FORMAT. 

When providing graphics such as logos to your designer, it is best to give them in a Vector graphic. Common formats include .ai or .eps files that have been created in a vector program, preferably Adobe Illustrator. Photographic images should be provided at its highest resolution and size. Common formats in a high resolution include .psd, .eps, and .jpg.