Bitmap vs. Vector-Based Graphics

There are two main categories of graphic images: bitmap and vector.

Bitmap images, also referred to as raster images, are pixel-based. This means that location and color information about the image is stored in individual pixels within a grid. Figure 5.1-1 shows a small blue arrow image at its actual size. Figure 5.1-2 shows the same image magnified. The upper left quadrant of Figure 5.1-2 shows the individual pixels of the image. As the figure illustrates, each pixel has an assigned color; some pixels are white, while other pixels are blue. The information stored in a bitmap image regarding pixel location and color is what forms the image. Bitmap images are edited at the pixel level; in other words, the color of any one pixel can be changed. Additional attributes of bitmap images include:

  1. Bitmap images are usually created and edited in "photo" or "paint" programs such as Adobe Photoshop.
  2. Bitmap images are mapped to a grid.
  3. The size of the image is based on the image's resolution.
  4. Bitmap images are not easily scalable.
  5. Bitmap images are used for photorealistic images and, therefore, may involve complex color variations.

Arrow Image

Figure 5.1-1: Arrow Image, Actual Size


Arrow Image with Pixel Grid

Figure 5.1-2: Magnified Arrow Image with Pixel Grid

 

Vector images are mathematically-based. All lines, shapes, etc. (also called objects) of a vector-based image are independent of one another. Figure 5.1-3 shows an image of a rose (actual size). Figure 5.1-4 shows one leaf of the same rose magnified, along with the paths and handles used within vector images. Additional attributes of vector-based images include:

  1. Vector-based images are usually created and edited in "draw" or "illustrate" programs such as Adobe Illustrator.
  2. Vector-based images have smooth edges.
  3. Vector-based images create curves or shapes.
  4. Vector-based images are good for precise illustrations, but are not as good for photorealistic images.
  5. Vector-based images are easily scalable, due to their use of mathematic formulas.

Rose Sample

Figure 5.1-3: Rose sample


Rose Leaf with Handles

Figure 5.1-4: Rose Leaf with Handles