The design of portable image processing algorithms depends on the availability of standard specification languages. In many cases, such specification languages have taken the form of subprogram libraries. In this paper, we discuss a different approach to language standards, namely, the use of mathematical system, an image algebra, for specifying image processing algorithms. The AFATL image algebra, capable of specifying all finite gray level image processing algorithms, provides a variety of mathematical tools with which to manipulate images at a high level. This paper discusses the unique benefits of using such a mathematical system as a common interface specification rather than using typical subprogram libraries, and presents the basic operations and operands of the AFATL image algebra. In addition, we look closely at an imbedding of the image algebra into the Ada programming language. This imbedding provides the basis for a portable high-level image processing language. Benefits and drawbacks of both an Image Algebra Ada (IAA) translator and an Image Algebra Interpreter (IAI) for a sublanguage of IAA are discussed. We close with an analysis of prospects for future use of image algebra in algorithm specification.