There are two methods used by computers to create and store artwork, and they reflect the file formats used by paint and draw programs. Which type of program is right for you depends on the type of artwork you intend to create.
If painting is more natural to you, or if you have a hand or flatbed scanner or send your film out to be processed and scanned onto Photo CDs, then you need a paint program to create, manipulate or edit your images. The Paintbrush program that comes with Microsoft Windows is a paint program. Some other paint programs are Adobe Photoshop, Corel PhotoPaint, and Fractal Painter, and there are many more.
The file format used by paint programs is called a “bitmap.” A bitmap image is made up of dots, just like in the newspaper comic pages or the images on your computer monitor, except that they’re square rather than round. Bitmap images are also called “raster” images. You can think of a bitmap image as having been created on a piece of graph paper with many tiny squares. Each square contains a bit of the image.
If the image is only black and white, each tiny square is either black or white. If the image is a scanned-in grayscale photograph, each tiny square is one of 256 different shades of gray. And if the image is either a scanned-in color photograph or a picture you have created in a color paint program, each tiny square contains a color. How many colors each square is capable of depends on your video hardware and the capabilities of your paint software.
The term “paint” program fits well because the pictures you create become part of the imaginary “canvas” of your computer, just like creating with real paint. To make changes or edit a bitmap image, each individual square or “pixel” (short for “picture element”) must be altered, either individually or in groups. If you draw a red square and partially cover it with a blue circle, the two objects simply become an image made up of tiny red and blue pixels “painted” onto a white canvas.
Bitmaps look fine at the size they were originally created or scanned, but to enlarge them, the computer must actually add pixels to the ones already there, and must do its best to guess where they should go. On diagonal lines, which are actually made up of tiny squares, the guessing game is not very accurate, and the result is the “stairstep” jaggies that make it obvious an image is computer-generated. If you make a bitmap smaller, the computer tosses out some of the squares, and again must guess which ones to eliminate. The result is not nearly as bad as enlarging an image--in fact, sometimes the image looks better. But the best bet is to create or scan a bitmap image at the size you intend to eventually print it out.
If your images need to be more precise, like engineering or technical drawings, or need to be edited after having been created, then a draw program would be more suited to your needs. Examples of draw programs are CorelDRAW!, Adobe Illustrator, and Macromedia FreeHand, among many others.
The images resulting from a draw program are called “object” or “vector” images. They are stored by the computer as mathematical formulas, not as dots, and as a result they are always crystal clear no matter how much you shrink or enlarge them — no jaggies. In addition, draw files can easily be edited long after they were originally created, as the objects making up the image always stay distinct and separate from each other. It’s something like cutting shapes out of construction paper and forming them into the components of your image, and then stacking them on each other in layers to form the end product. However, unlike real “cut-out” objects, computer-drawn objects can be filled in with colors, blends of colors, or patterns, and their outlines can be varying colors, thicknesses, and patterns. If you draw a red square and partially cover it with a blue circle, the two objects stay distinct from each other, as though they had been cut from paper and laid one on top of the other. You can change colors, make each one larger or smaller, or change their stacking order — that is, bring the square in front of the circle — at any time.
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