|Understanding vector graphics and bitmap images
In order to determine what kind of image is best suited for your project, it's helpful to know a little about the content types you'll find on the Clip Art and Media site.
There are two types of images that are most common: clip art and photographs. Clip art uses the Windows Metafile (WMF) file format, which is a type of vector graphic. The photographs on the site use the Joint Photographics Expert Group (JPG) file format, which is a type of bitmap image.
Vector graphics, such as clip art images, are formed by lots of individual objects. These objects, made up of lines, curves, and shapes, are placed on top of each other to create an image. Imagine many different pieces or parts of a clip layered to make one image.
One advantage of vector graphics is that they are scalable. Consider this clip art of pie. You can move, resize, or change the color of the pie and not compromise the quality of the clip art. You can increase and decrease the size of the clip art and it will remain sharp and crisp on your screen and in print.
Bitmap images, such as photographs, are made from a series of small dots, much like a piece of graph paper with certain squares filled in to form shapes and lines. These dots are called pixels, and each pixel contains one color. Each bitmap image contains a fixed number of pixels. So every inch of a bitmap image contains a certain number of pixels, also referred to as an image's resolution. The more pixels per inch, the higher the resolution. Bitmap images are resolution-dependent.
Consider this photograph of a pie. When you enlarge the photo, your computer program must guess where to put the extra pixels necessary to fill out the larger image. That is why a photograph can appear jagged or blurry when you try to enlarge it. However, unlike most vector graphics, bitmap images display complex gradations of color and shades, which is why they are such a popular file type.
Because of its scalability, clip art looks great both in print and online. Photographs can be printed, too, depending on the resolution of the image. They are commonly found on the Internet.
For best results, consider how the image will be used in the final product and then choose the appropriate image type.