If a bitmap image is enlarged too much or if an image with screen resolution is used in a printed project, you can see the rows of pixels that make up the image. Images can come in a variety of formats. Common image file formats include TIFF , PICT , BMP , WMF , GIF , JPEG and EPS . Each format is best-suited for a particular use. PDF files are not actually image files but they are sometimes grouped together.
Images also come in a variety of color modes with corresponding bit depths .
Each one of these color modes has a specific use. Duotones, duographs, tritones and quadtones are usually created by combining grayscale images with spot colors to create different effects. Indexed color mode images are ideal for web graphics. These images contain less than 256 colors and, as a result, have smaller file sizes. Before a project can be professionally output to film or printed, it is best to preflight the project, which includes graphics.