When creating or working with a logo — or any other non-photographic line art — a vector image will almost always look sharper on press than a raster (or bitmap) image. Why is this?
• A raster image is made up of pixels or little dots. A pixel is the smallest element that can be individually processed on a display screen. Once an image is created in pixels, its resolution is set. So a raster image at 300 dpi, which works great for photographs, will not print cleanly and sharply (see above right). Even when imaged on a printing plate (typically 2400 dpi), it’s still the same resolution at which it was created. If you enlarge a raster image, it becomes even more jagged/fuzzy.
• A vector image, on the other hand, is created from a mathematical description, like plotting points on a graph (see below). This generates more precise shapes because it is not turned into pixels until the moment the printing plate is made. Vector images can be scaled to any size and still print sharply (see above left). They are imaged at the resolution of the printing plate, or 8 times higher than the typical 300 dpi image.
The Bottom Line…
To make sure your logo comes out crystal clear, do not use Photoshop to create it. Photoshop is specifically designed to create and edit photos, which are raster images. So reserve Photoshop for photos, and use Illustrator for logos and other vector line art. When requesting a logo from a third party, ask for the vector version.
The only exception is special effects that might need to be applied in Photoshop. In those cases, use a layered Photoshop file so you can keep vector-based type and line art (Smart Vector Objects) separate from photos or other raster components. And place the layered PSD into your design layout.