Chain code
Encyclopedia
A chain code is a lossless compression algorithm for monochrome
image
s. The basic principle of chain codes is to separately encode each connected component, or "blot", in the image. For each such region, a point on the boundary is selected and its coordinates are transmitted. The encoder then moves along the boundary of the image and, at each step, transmits a symbol representing the direction of this movement. This continues until the encoder returns to the starting position, at which point the blot has been completely described, and encoding continues with the next blot in the image.
This encoding method is particularly effective for images consisting of a reasonable number of large connected components.
Some popular chain codes include the Freeman Chain Code of Eight Directions (FCCE), Vertex Chain Code (VCC), Three OrThogonal symbol chain code (3OT) and Directional Freeman Chain Code of Eight Directions (DFCCE).
A related blot encoding method is crack code. Algorithms exist to convert between chain code, crack code, and run-length encoding.
Monochrome
Monochrome describes paintings, drawings, design, or photographs in one color or shades of one color. A monochromatic object or image has colors in shades of limited colors or hues. Images using only shades of grey are called grayscale or black-and-white...
image
Image
An image is an artifact, for example a two-dimensional picture, that has a similar appearance to some subject—usually a physical object or a person.-Characteristics:...
s. The basic principle of chain codes is to separately encode each connected component, or "blot", in the image. For each such region, a point on the boundary is selected and its coordinates are transmitted. The encoder then moves along the boundary of the image and, at each step, transmits a symbol representing the direction of this movement. This continues until the encoder returns to the starting position, at which point the blot has been completely described, and encoding continues with the next blot in the image.
This encoding method is particularly effective for images consisting of a reasonable number of large connected components.
Some popular chain codes include the Freeman Chain Code of Eight Directions (FCCE), Vertex Chain Code (VCC), Three OrThogonal symbol chain code (3OT) and Directional Freeman Chain Code of Eight Directions (DFCCE).
A related blot encoding method is crack code. Algorithms exist to convert between chain code, crack code, and run-length encoding.