CRISP: Coarse-Grained Reconfigurable Image Stream Processor for Digital Still Cameras and Camcorders

To design the hardware for image signal processing pipelines in digital still cameras (DSCs) and video camcoders, it is a dilemma for conventional solutions, such as application-specific integrated circuits (ASICs) and digital signal processors (DSPs), to achieve high processing capability at low cost while maintaining high flexibility for various algorithms. With the observation of the characteristics of image signal-processing pipelines, including the different requirements for different operation modes and the algorithmic similarity of image-processing tasks, a new coarse-grained reconfigurable image stream processor (CRISP) is proposed in this paper. The design idea is to devote low-cost hardware for the requirements in the preview mode and add some hardware resources for higher flexibility and processing capability in the picture-taking mode. With the coarse-grained reconfigurable stage processing elements designed for image signal-processing tasks and the reconfigurable interconnection unit with unified communication protocol, CRISP can be reconfigured as an efficient dedicated hardware in the preview mode, and it can act like a flexible DSP for the picture-taking mode with different contexts. Implementation result shows that the core (die) size is 5 mm² (7.72 mm²) with TSMC 0.18-mum process, and the power consumption is 218 mW at 1.8 V. At the working frequency of 115 MHz, the processor is capable of processing 11 M-pixel still images at 10 fps for DSCs or 1920 times 1080 video frames at 55 fps for camcorders. CRISP can execute image pipelines 83 times faster than the state-of-the-art DSP with only about one-tenth die size.