| High dynamic range image (HDRI) shows richer layers and more realistic lighting effects than traditional picture, it has wildly potentially uses in many fields. Although the high dynamic range display devices have been developed recently, the dynamic range could be displayed still limited. So, most of display devices can not support high dynamic range output. In order to solve the problem, many tone mapping algorithms were proposed to bridge the gap between HDRI’s and low dynamic range devices.Firstly, briefly introduced some concepts of tone mapping method for high dynamic range images and summarized current HDRI tone mapping methods; secondly, focus on the typical HDRI file format--the Radiance RGBE format, researching how to read the Radiance RGBE file through the file pointer after color space conversion, after that, valuable information such as brightness value are obtained; Finally, in order to adapt to the low dynamic range of the display device, Adaptive Logarithmic Mapping algorithm was programmed and was applied to compress the dynamic range of HDRIs. Part of equations of the algorithm was optimized for the purpose of improving the computation efficiency; useful information after dynamic range compression were used to contruct bmp format image which could displayed in the traditional display system, source code of main processsing functions mentioned above are opened in the context of this paper.Experimental results indicate that, after processing, the high dynamic range image shows more details; especially in dark areas and high brightness area are shows better image display quality. Visual effects are improved greatly compared with raw Radiance RGBE files. From the other hand, after compression, images shows better performance by drawing brightness probability distribution graph, the luminance values of all compressed pixels is within the dynamic range of display device, lighting contrast also keeped at the same time. |
PDF Full Text Request