Binary Image Transforms: An old twist in Image Processing revisited

Abstract

Image processing techniques (and papers describing them) have evolved rapidly in recent years. Lately, publications in image processing have underscored advances in compression, restoration, and enhancement of gray level and color coded image information using dedicated pipeline processing and systolic array architectures. These new algorithms and specialized hardware have been developed and applied to such real-time tasks as automated testors on manufacturing lines and robotic vehicle guidance systems. Often overlooked is the art of binary image processing. A review of binary processing techniques is valuable in understanding the the basic operating principles of high-speed optical inspection devices in particular and many pipeline array processing devices in general. The class of binary image transforms covered here was originally developed for topological operations on thresheld image data. These non-linear operations are based on boolean transformations of a pixel and its eight adjacent neighbors (in a discrete Cartesian plane) and are named morphological transforms by some authors. A straightforward way to visualize such transforms is outlined in the paper and will be demonstrated at the conference. The demonstration program package was written using the IBM Personal Computer BASIC language and was presented as an educational tool in a graduate level course in image processing. The skeletal program included in the text was enhanced to allow real-time demonstration of these transform techniques and encourages readers to experiment and develop their own lookup tables and image transforms. Understanding the function and generation of these lookup tables, which can provide any arbitrary boolean combination of the nine binary values available from a pixel and its eight Cartesian neighbors, is the key to grasping the image transforms illustrated here. Examples in the paper and presentation give the reader an idea of the power and flexibility these transforms provide in image processing and feature recognition tasks. An overview of some relevant image processing topics precedes the discussion of binary transforms and the transform simulator.