Vector images are either created in a vector-drawing program or have been converted from a bitmap image. A bitmap image is made up of pixels , or tiny squares, on a fixed grid. Bitmap images are resolution dependent. The higher the resolution, the more tiny pixels exist on the image's grid and the more detail an image can display. 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.