Dynamic Range Enhancement By Multi-Exposed Images

With the popularization of PC and the Internet, digital camera has become a device frequently used in image acquisition and image input in computer. When taking a picture, we will often be encountered with a scene of large dynamic range, which cannot be fully recorded by a DC because of the limitation of CCD and ADC. When the dynamic range of a scene is wider than that of a DC, photographers will often change camera exposure to control the captured range of brightness, but whatever the exposure is, there will always be some under-exposed and over-exposed areas in a picture, which results in the loss of highlight or darkness details.An algorithm of dynamic range enhancement based on camera response function and multi-exposure images is proposed to address this problem. A set of images is taken upon the same scene and well combined through the algorithm to compose a single image with different intensity details together. The main idea of the algorithm is to divide images into blocks and select best informed image blocks with regard to camera response curve and then fuse them up with a global fusion function to remove block discontinuity. Through the algorithm, an image of abundant brightness information can be obtained.It is the most critical part of the algorithm to select and fuse the most informed image blocks. From the analysis of imaging process, we propose a way of image information measurement based on camera response curve and form an assessment function upon image information condition and block continuity condition. After selecting the best informed image blocks, a weighted average fusion method is...