Energy scalable approximate DCT architecture trading quality via boundary error-resiliency

High energy-efficiency is an imperative requirement for today´s portable multimedia devices. Most image/video processing devices employ energy-devouring Discrete Cosine Transform (DCT) unit that limits their performance. We propose a novel low-complexity DCT architecture that exploits non-significance-driven complexity reduction techniques namely neighbor pixel similarity (NPS) and constant multiplication factor (CMF). Further, quality-energy tradeoff is achieved via error-resiliency at image-boundaries. We also present a novel quality metric PMSE (Perceivable Mean Square Error) that quantifies perceivable error. Our architecture consumes 49.2% less energy at the expense of 1.43dB less PSNR and requires only 45.4% area over well-known DCT architectures.