Local Contrast Stretch Based Tone Mapping For High Dynamic Range Images

We live in a world with high dynamic range scenery. The Dynamic Range of a scene, image or an imaging device is defined as the ratio of their highest to the lowest luminance or signal level. Our human visual system is well adapted to cope with this high contrast environment so that we can see clearly both dark and bright regions in the same scenery. The high dynamic range radiance map is the image file, making it possible to accurately record the full dynamic range of a real scene. However directly capturing the full dynamic range of the scene would be a hard task for a conventional digital cameras. High Dynamic Range radiance map of a scene can be generated by using a sequence of Low Dynamic Range images of the same scene taken under different exposure intervals. Due to the dynamic range of a display device is very low. In order to reproduce High Dynamic Range maps on Low Dynamic Range visualization devices, mapping or tone reproduction techniques are used to map High Dynamic Range values to Low Dynamic Range values. Tone mapping technology is to guarantee the quality of image formation, compression its dynamic range, to make low dynamic range display equipment can output. And this paper studies focus is tone mapping technology.In the paper, we first review the techniques used to capture high dynamic range image data, which is also know as radiance map recovery. And then introduced the predecessor's research is tone mapping algorithm, its main into global tone mapping algorithm and local tone mapping algorithm. Finally, this paper brings forward local contrast stretch based tone mapping algorithm. This algorithm is very good solved high dynamic range radiance map processed tone mapping algorithm local contrast declines.Local Contrast Stretch Based Tone Mapping for high dynamic range images, the first is the dynamic range of global, and then to logarithmic mapping each pixel image in the window of contrast stretch. Experimental results show that after the proposed based on local contrast stretch algorithm processed image not only kept the high dynamic range scene in details, but haven't changed the whole image under the condition of contrast, expand the image local contrast.