Graphic designers spend all their day dealing with a variety of file types. Unless the designer is creating a new logo for the client from scratch, the designer will likely depend on the client to provide the logos in the correct format in order to get the ideal result. As a client, it is good to be informed about two file types to ensure the best quality of art. These two file categories are vector and raster. Raster is also known as…everything else.
A raster image has a quality that is “static”. This means the image condition, such as resolution, is inherent and cannot be improved upon by the designer. The most common file of this type is a jpeg. If the image quality is low, you will see the “stair step” effect on the edges of the art work such as a logo. This stair step effect is visible when there are a small number of pixel squares available to make up the details of the image. Blowing up the image will enlarge the stair steps as well. The more pixels that make up the image, the higher the resolution will be and each pixel square will be less noticeable. In video games, this is like going from the graphics quality of Atari to the X-Box. However, even if the quality of the raster logo is high, the white square surrounding the logo may still have to be edited out in a program such as photoshop unless the art the logo is placed on is also white. This increases the chance of being charged more for art time.
A vector image is not composed of pixel squares. Rather, the image is “dynamic”. This means your logo size can be increased without degrading the quality of the image. The file types that indicate a vector image are .eps and .ai (Adobe Illustrator). PDF files may or may not preserve the editable qualities of a vector file as well. I should also point out that changing the file name, such as adding “.eps” to the end of the file does not change file from a raster to a vector image. A genuine vector file requires being created in a vector program such as Adobe Illustrator or Corel Draw.
To sum up, If in doubt, provide your designers with vector files of your logo if you have them. I guarantee they will be happy with you and you will also allow them to produce a better quality image in a shorter amount of time, which can also save you money.