Research Of High Dynamic Range Image Display And Compression

In recent years, high dynamic range imaging (HDRI) has become a topic of intense research interest in the fields of global illumination, realistic rendering, remote sensing, digital camera etc. It provided a method for displaying high dynamic range image based on local adaptation, and developed a scheme for data compression on high dynamic range image based on JPEG2000 standard.The solution for displaying high dynamic range image was to compress the high dynamic range of image pixel values into the displayable range (low dynamic range) of the display device. The visual system is able to perceive details in an environment with a high dynamic range by means of local adaptation. A region-based method for calculating local adaptation luminance was proposed to imitate the local adaptation mechanism. It segmented image with region growing. Then local adaptation luminance was computed via region-based bilateral filter. It outputted low dynamic range images in conjunction with tone mapping operator. The resulting images preserve details without halo artifacts.The row size of a high-dynamic range image brings about problems in storage and transmission, as high-dynamic image files encode the color gamut and dynamic range of the original scene. A compression method was proposed for high-dynamic still images by extending JPEG2000 encoder. Based on tone mapping, a logarithmic mapping transformed three 32-float pixels to three 16-bit integer data, then the data was fed to JPEG2000 encoder. The result indicates that the scheme has a high coding efficiency, while improving subjective quality.