A Concurrent Image Filtering Project for Undergraduate Computer Science Education

摘要

Parallel and distributed computing has emerged as an increasingly important topic in Computer Science education driven largely by the predominance of multi-core systems, cloud computing systems and the use of GPU's for general computation. As fundamental concepts of concurrency become more tightly integrated with undergraduate education there is a heightened need for projects that have both a practical and accessible parallel solution. This paper presents a parallel programming project using Java that is based on median filtering digital images. The project is designed for use in an undergraduate computer science curricula and has been used in a programming languages course. The project has appealing features since 1) the problem domain lies within the field of multimedia and digital image processing 2) the problem domain is easily understood 3) the sequential solution is straightforward to implement 4) the output can be visualized since the output is a digital image and 5) parallelization provides a clear speedup where the controlling parameters can be tuned to exhibit both the cost and benefit of synchronization. Image processing is a field of study within the broader domain of signal processing where a digital image, commonly referred to as the source image, is processed to produce an output digital image, which is commonly referred to as the destination image. Digital images are often filtered to produce an image that is more suitable for later computation or to produce an image that is more aesthetically or artistically pleasing than the source image. Median filtering is a non-linear process based on a straightforward statistical analysis of a local sub-region of an image. This paper gives an overview of median filtering digital images, provides a naive sequential solution, a design for parallelization, a discussion of the performance gains and concludes with a discussion of issues related to using the project in an undergraduate educational setting.