Research On High Dynamic Range Image Inverse Tone Mapping

With the improvement of video processing technologies and capability of display panels as well as the growing demand for visual quality,high dynamic range image/video processing technology emerges which has better display effect than standard dynamic range content.As a key technology in the field of video services,HDR effectively promotes the technological innovation in the entire industry including shooting,production,compression and transmission,which is currently an important driving force for improving video quality and user experience.Taking into account the characteristics of HDR,this paper studied the subjective quality evaluation methods of tone mapping and proposed an improved inverse tone mapping algorithm.At the end,a transcoding system transforming SDR to HDR was integrated by using the principle of pipeline.In this paper,we firstly made a comprehensive introduction of HDR from the aspects of the basic characteristics,transform functions of HDR,a variety of HDR formats,the solutions to compatibility between SDR and HDR,the production flow of HDR,etc.Therefore,we can have a comprehensive and in-depth understanding of the entire HDR ecosystem.At present,there is not a normative and systematic HDR ecosystem in the field of video services in China.The market share of HDR display panels shows that a transition solution is needed to promote the HDR video service industrial chain.Tone mapping is currently a suitable solution.In this chapter,we presented a novel subject quality evaluation scheme for tone mapped video that provides a reference to major engineering tests for tone mapping.In order to solve the problem of lack of HDR sources,this paper put forward an improved piecewise method based on linear inverse tone mapping algorithm,which improves the contrast of single frame image.Then,two objective quality metrics,DRIIQM and HDR-VDP-2 were used in our objective test for video quality evaluation.According to the results of performance testing,the proposed algorithm achieved ideal subjective as well as objective quality under the premise of keeping lower time complexity.Finally,to solve the problem of too much intermediate in the process of HDR production which takes up huge storage space,a complete ultra high definition video transcode system based on vapoursynth was presented.Combining with the principle of pipeline,the proposed inverse tone mapping algorithm,the toning module and audio/video demuxer module were integrated into our system.