Tone Mapping For High Dynamic Range Image And Its Assessment

Tone mapping technology compresses the dynamic range of high dynamic range images blow to the dynamic range of output device.This technology is the main point of high dynamic range image research field.This thesis systematically studies the tone mapping algorithm and the assessment index of tone mapping and compares proposed algorithm with typical algorithm through experiments we designed.The main works and achievements of this thesis can be summarized as follows:1.We proposed edge-based support region computing algorithm for local tone mapping.Conventional dodging-and-burning in Reinhard's photographic algorithm often suffer from halo artifacts or a loss of details,which is due to the failure of distinguishing the regions with few strong edges from the ones with lots of weak details during the local mapping.In this paper,we propose an edge-based adaptive support region computing algorithm for local tone mapping.The proposed algorithm operates maximum filters with gradually extending size for the edge of the original image to compute support regions,which manages to make a distinction between weak details and strong edge effectively,and could get more appropriate support regions.Experiments show that the proposed algorithm can not only preserve more details but also run much faster.2.For the problem of the statistical model based assessment index of naturalness may not be suitable for room scene,we proposed bright-dark relationship based assessment index of luminance consistency which is consistent with the perception of human visual system and independent with dynamic.According to the perception for luminance of human visual system,the proposed index extracts local brightest and darkest points,and computes the bright-dark relationship by matching those points.3.We proposed the compositive assessment index for tone mapping by combining the proposed bright-dark relationship based assessment index of luminance consistency and local structural similarity index.The compositive assessment index obeys the standard of tone mapping and leads to a result more similar to the perception of human visual system,besides the compositive assessment index is very robust.