There are two types of images used in printing: raster and vector images. Though both can be used in any printing project, each image type has different requirements because they are very different from each other.
Photographs and other pixel-based artwork are known as raster (or bitmap) graphics. This artwork is created from groups of tiny squares or pixels, and print in groups of dots. When raster graphics are enlarged, the quality is reduced, and images may appear pixelated. Because of the way raster graphics are created, commercial print projects require a minimum resolution of 300dpi.
Unlike raster images, vector graphics can be scaled to any size without losing quality. That’s because the format uses mathematical formulas to enlarge or reduce the size and is not pixel-based. Vector images typically include Adobe Illustrator files, some clipart, and PDFs with fonts converted to outlines.
Keep in mind that many special effects (like gradients and drop shadows) used in Adobe Illustrator are raster based. Your file sizes will be much larger, and you must have all your settings correct to avoid problems during printing. If you need help flattening vector files with raster elements, contact us, and we can walk you through the process.