MCM-SR: Multiple Constant Multiplication-Based CNN Streaming Hardware Architecture for Super-Resolution

Convolutional neural network (CNN)-based super-resolution (SR) methods have become prevalent in display devices due to their superior image quality. However, the significant computational demands of CNN-based SR require hardware accelerators for real-time processing. Among the hardware architectures, the streaming architecture can significantly reduce latency and power consumption by minimizing external dynamic random access memory (DRAM) access. Nevertheless, this architecture necessitates a considerable hardware area, as each layer needs a dedicated processing engine. Furthermore, achieving high hardware utilization in this architecture requires substantial design expertise. In this article, we propose methods to reduce the hardware resources of CNN-based SR accelerators by applying the multiple constant multiplication (MCM) algorithm. We propose a loop interchange method for the convolution (CONV) operation to reduce the logic area by 23% and an adaptive loop interchange method for each layer that considers both the static random access memory (SRAM) and logic area simultaneously to reduce the SRAM size by 15%. In addition, we improve the MCM graph exploration speed by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.4\times $ </tex-math></inline-formula> while maintaining the SR quality through beam search when CONV weights are approximated to reduce the hardware resources.