Photoshop
Digital Graphics
Vector Graphics
Object oriented or vector graphics refers to images based on mathematical calculations that are represented by paths. Vector graphics are typically more versatile than bitmap or resolution-dependent graphics because they are scalable and generate smaller file sizes.
Vector graphics are referred to as resolution-independent because they do not plot images on a pixel-by-pixel basis and so are not tied into a monitor's resolution. Vector images describe images in terms of shapes, lines, curves, points, colours, length, etc. These images rely only on the resolution of an output device (like a printer for example) to determine their final resolution. Some common vector-based applications are Macromedia Freehand, Adobe Illustrator, and Macromedia Flash. Examples of images suitable for vector graphics are logos and type.
To create a one-inch black and white circle with a bitmap image, you might have a grid of dots one inch down and one inch across, with 72 dots per inch. This gives you about 5000 dots to play with (72x72=5184 pixels). Regardless of the pattern of pixels (circle, square, checkerboard), this raw file will always be the same number of bytes before compression. If you enlarge how that image is displayed on the screen, it will appear jagged and distorted. (The example here has been enlarged 400% to show the imaginary pixel grid.)
To create that same one-inch black and white circle as a vector graphic, you would define the center point of the circle, the radius, and the colour. That's about it. If you want to make it larger, change the value of the radius; the file size will not get larger and the image will not distort. This is an advantage of vector graphics. However, they are not useful for complex images such as photographs. The advantage there goes to bitmaps.
While Photoshop primarily outputs bitmap images, it also has the ability to create vector shapes that you can modify and scale while editing your images with no loss of quality.
You can view an example of a Flash vector file vs. a bitmap file here.
Vector Graphics Summary
- There are two main types of digital graphic files: bitmap and vector.
- Vector files are resolution-independent.
- Vector graphics use mathematical formulae to create the image, not pixels on a grid like bitmap images.
- Simple vector images can be quite small compared to bitmap; complex images like photographs are difficult and inefficient with vectors.
- Bitmap is still more common than vector.
- Vector images can scale without loss of detail or a change in file size.
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