OpenCV on TI’s DSP+ARM®

In today’s advancing market, the growing performance and decreasing price of embedded processors are opening many doors for developers to design highly sophisticated solutions for different end applications. The complexities of these systems can create bottlenecks for developers in the form of longer development times, more complicated development environments and issues with application stability and quality. Developers can address these problems using sophisticated software packages such as OpenCV, but migrating this software to embedded platforms poses its own set of challenges. This paper will review how to mitigate some of these issues, including C++ implementation, memory constraints, floating-point support and opportunities to maximize performance using vendor-optimized libraries and integrated accelerators or co-processors. Finally, we will introduce a new effort by Texas Instruments (TI) to optimize vision systems by running OpenCV on the C6000TM digital signal processor (DSP) architecture. Benchmarks will show the advantage of using the DSP by comparing the performance of a DSP+ARM® system-on-chip (SoC) processor against an ARM-only device. OpenCV on TI’s DSP+ARM platforms: Mitigating the challenges of porting OpenCV to embedded platforms Introduction OpenCV is a free and open-source computer vision library that offers a broad range of functionality under the permissive Berkeley Software Distribution (BSD) license. The library itself is written in C++ and is also usable through C or Python language applications. Thousands of developers use OpenCV to power their own specialized applications, making it the most widely-used library of its kind. The OpenCV project is under active development, with regular updates to eliminate bugs and add new functionality. The mainline development effort targets the x86 architecture and supports acceleration via Intel’s proprietary Integrated Performance Primitives (IPP) library. A recent release also added support for graphics processing unit (GPU) acceleration using NVIDIA’s Compute Unifi ed Device Architecture (CUDA) standard. OpenCV’s greatest asset is the sheer breadth of algorithms included in its standard distribution. Figure 1 on page 2 shows an incomplete list of some of the key function categories included in OpenCV. These range from low-level image fi ltering and transformation to sophisticated feature analysis and machine learning functionality. A complete listing of every function and use case is beyond the scope of this article, but we will consider the unique requirements of developers in the embedded vision space. For these developers, OpenCV represents an attractively comprehensive toolbox of useful, well-tested algorithms that can serve as building blocks for their own specialized applications. The question then becomes whether or not OpenCV can be used directly in their embedded systems. Despite its original development focus for use with PC workstations, OpenCV can also be a useful tool for embedded development. There are vendor-specifi c libraries that offer OpenCV-like capabilities on various embedded systems, but few can match OpenCV’s ubiquity in the computer vision fi eld or the sheer breadth of its included algorithms. It should come as no surprise that OpenCV has already been ported to the ARM® architecture, a popular CPU choice for embedded processors. It’s certainly possible to cross-compile the OpenCV source code as-is and use the result with embedded devices, but memory constraints and other architectural considerations may pose a problem. This white paper will examine some of the specifi c obstacles that must be overcome for OpenCV to achieve acceptable performance on Joseph Coombs, Applications engineering, Texas Instruments Rahul Prabhu, Applications engineering, Texas Instruments W H I T E P A P E R