Block-Based Gradient Domain High Dynamic Range Compression Design for Real-Time Applications

Due to progress in high dynamic range (HDR) capture technologies, the HDR image or video display on conventional LCD devices has become an important topic. Many tone mapping algorithms are proposed for rendering HDR images on conventional displays, but intensive computation time makes them impractical for video applications. In this paper, we present a real-time block-based gradient domain HDR compression for image or video applications. The gradient domain HDR compression is selected as our tone mapping scheme for its ability to compress and preserve details. We divide one HDR image/frame into several equal blocks and process each by the modified gradient domain HDR compression. The gradients of smaller magnitudes are attenuated less in each block to maintain local contrast and thus expose details. By solving the Poisson equation on the attenuated gradient field block by block, we are able to reconstruct a low dynamic range image. A real-time Discrete Sine Transform (DST) architecture is proposed and developed to solve the Poisson equation. Our synthesis results show that our DST Poisson solver can run at 50 MHz clock and consume area of 9 mm² under TSMC 0.18 um technology.