This paper describes a new effort to evaluate parallel architectures applied to knowledge-based machine vision. Previous vision benchmarks have considered only execution times for isolated vision-related tasks, or a very simple image processing scenario. However, the performance of an image interpretation system depends upon a wide range of operations on different levels of representations, from processing arrays of pixels, through manipulation of extracted image events, to symbolic processing of stored models. Vision is also characterized by both bottom-up (image-based) and top-down (model-directed) processing. Thus, the costs of interactions between tasks, input and output, and system overhead must be taken into consideration. Therefore, this new benchmark addresses the issue of system performance on an integrated set of tasks. The Integrated Image Understanding Benchmark consists of a model-based object recognition problem, given two sources of sensory input, intensity and range data, and a database of candidate models. The models consist of configurations of rectangular surfaces, floating in space, viewed under orthographic projection, with the presence of both noise and spurious nonmodel surfaces. A partially ordered sequence of operations that solves the problem is specified along with a recommended algorithmic method for each step. In addition to reporting the total time and the final solution, timings are requested for each component operation, and intermediate results are output as a check on accuracy. Other factors such as programming time, language, code size, and machine configurations are reported. As a result, the benchmark can be used to gain insight into processor strengths and weaknesses and may thus help to guide the development of the next generation of parallel vision architectures. In addition to discussing the development and specification of the new benchmark, this paper presents the results from running the benchmark on the Connection Machine, Warp, Image Understanding Architecture, Associative String Processor, Alliant FX-80, and Sequent Symmetry. The results are discussed and compared through a measurement of relative effort, which factors out the effects of differing technologies.