The Circuit Design Of Wide Dynamic Range Tnoe Mapping

Wide dynamic range image have rich information about detail and contrast of the scene. When displayed on the low dynamic range display, the mismatch of the dynamic range will result in loss of detail of wide dynamic range image. When the wide dynamic range image was pocessed by tone mapping circuit, the detial will be reserved, so the problem of mismatch of the dynamic range will be solved.Durand’s tone mapping algorithm is analyzed and symplified. It is find that the complexity of algorithm mainly comes from floating-point image processing. Therefore, floating-point arithmetic is optimized and improved, before converting it into a fixed-point algrithm the loss of TMQI must be less than 0.01. Then hardware circuit design of the algorithm is completed, the key operator of it include color interpolation, exponential and the logarithm operator,20 integer division, color correlation and bilateral filter. Parallel and pipelined architecture is adapted for the combinational logic circuit design of tone mapping, it will meet the real-time processing requirements.Finally, based on the DE2-115 board platform and TRDB-D5M camera, the video capture platform will be completed to verify the performance of the circuit. Experimental results show that the circuit supports that the image with 1024×768 resolution can be processed by 40MHz and the frame rate can be 30fps, the circuit consume 18324 logic cells and 86466 memory cells. After comparing simulation result of hardware and software model, results show that the average loss of TMQI is no more than 0.005. The FPGA video capture platform shows that the TMQI of tone mapping mode is 0.11 more than linear mode.