Definition

• Raster based animation frames (and all raster images for that matter) are made up of individual pixels. These pixels each contain information about the color and brightness of that particular spot on the image. This is somewhat similar to the concept of pointillism in painting, with the sum of the points making up the totality of the picture or frame.
  
  

Uses

• Raster animation is used for depicting realistic representations of people, animals or places, rather than the more stylized, anime-style animation you might get with vector graphics. Raster animation is also use to create animation for logos and banners based on photos or drawings.
  
  

Difficulties

• One of the problems involved with creating raster-based animations on a computer is the enormous amount of computer power that is often involved in creating them. For example, a single frame of animation that is 400x300 pixels in size will have have a total of 120,000 pixels. Each of these pixels will have (depending on the color scheme being used) eight to 48 bits, meaning each frame might use as many as 5.76 million bits. This means that an animated 14-frame-per-second video of 20 minutes would have 2.02 trillion bits of information. Most films are larger than this with a higher frame rate.
  
  

Limitations

• A major difficulty with working with raster-based animation or images is that they are not infinitely enlargeable. This means that if you create a raster based animation at a certain size (400x300, for example), you will not be able to enlarge it to any significant extent without loss of resolution in the images. Vector graphics do not have this problem.
  
  

Sub-types

• There are two main sub-types of computer raster: drawn raster animation, which is created in programs like Photoshop or Painter, using the various painting and drawing tools. This type is often used for television or web page animations. The other type is created using rendered images from computer-generated imagery (CGI) programs like Maya or Cinema 4D. This is the type that is most often seen in movies.