The Good, the Bad and the Ugly: Practices and Perspectives on Hardware Acceleration for Embedded Image Processing

Modern embedded image processing deployment systems are heterogeneous combinations of general-purpose and specialized processors, custom ASIC accelerators and bespoke hardware accelerators. This paper offers a primer on hardware acceleration of image processing, focusing on embedded, real-time applications. We then survey the landscape of High Level Synthesis technologies that are amenable to the domain, as well as new-generation Hardware Description Languages, and present our ongoing work on IMP-lang, a language for early stage design of heterogeneous image processing systems. We show that hardware acceleration is not just a process of converting a piece of computation into an equivalent hardware system: that naive approach offers, in most cases, little benefit. Instead, acceleration must take into account how data is streamed throughout the system, and optimize that streaming accordingly. We show that the choice of tooling plays an important role in the results of acceleration. Different tools, in function of the underlying language paradigm, produce wildly different results across performance, size, and power consumption metrics. Finally, we show that bringing heterogeneous considerations to the language level offers significant advantages to early design estimation, allowing designers to partition their algorithms more efficiently, iterating towards a convergent design that can then be implemented across heterogeneous elements accordingly.