Research On Compatible Transmission And Reproduction Of Extended Gamut HDTV System

With the continous emerging of new upmarket TV displayers, after the definition of TV picture is improved, the demand to extend the color gamut of HDTV system became increasingly conspicuous, and it has become urgent to study and develop in this field. This dissertation began to study the wide color gamut HDTV system colorimetry foundementally and experimentally at the earliest in Chinese mainland. The acquired achievements lay foundation for academic research and simulation experiments of TV system color gamut, and established primary experimental research condition. It is applied basic research which is appropriately advanced in TV field.The work focuses on two aspects. One is to investigate how to transport wide color gamut video signals compatibly in current conventional color gamut HDTV system. The other is about how to display wide color gamut video signals on TV displays with relatively small color gamut. This dissertation also made great efforts on testing data and the establishment of experimental platform.It is unpractical to update current conventional color gamut TV system into wide color gamut system in the short term. The compatible transportation of wide gamut HDTV signals in current system is beneficial for steady transition from old system to the new one. This dissertation deeply analyzed the core technologies in the two international standards for wide gamut video currently available: ITU-R BT.1361 and IEC 61966-2-4, put forward a new set of three primary colors for wide gamut system by ergoding the range of primary colors permitted in ITU-R BT.1361. And this dissertation calculated the range of the wide gamut HDTV signal which can be compatibly transported in current ITU-R BT.709 conventional gamut HDTV system by linear extension based on the quantization range of IEC 61966-2-4.According to additive color mixture theory, this dissertation establishes 3D mathematical model for conventional color gamut, and compared it with the gamut of Pointer real surface colors in 3D colorimeter system. The results show that the reason why conventional gamut transportation system can't transport or reproduce all Pointer color gamut is not only because of the small scope of conventional color gamut but also because of the different coverage area between these two gamuts. This is useful for reference considering the need to thoroughly study the color coverage problem in 3D and coverage area.This dissertation put forward three systematic approaches for compatibly transportation of wide color gamut HDTV signals.One leads out the optimized chroma coordinates based on Pointer color gamut. These coordinates extend the gamut range of video signals with the advantage of small and close compression parameters for chroma signals, being robust to transportation disturbance and small reproduction difference. The second puts forward a kind of nonlinear quantization method for digital coding. This method can realize the compatible transportation of xvYCC wide gamut signals, and became the complement of opening part in IEC 61966-2-4. The third establishes new three primary colors system after the lead-out of three primary colors corresponding to the widest color gamut defined in ITU-R BT.1361. The color gamut coverage ratio will be 60.65% on the condition of compatible transportation in conventional gamut HDTV system. It can provide realistic and theoretical approach for laser projection imaging and future wide gamut HDTV sytem.The second part of the work realizes three gamut mapping arithmetics: truncation, SLIN and GCUSP, including the modification of linear conversion matrix, characteristic of display equipments, determination of gamut boundary and other core arithmetic. The theoretic analysis and experimental comparison show that GCUSP mapping method adopts nonlinear luminance compression, can realize the compression and mapping from Pointer color gamut to conventional gamut with good effects, and the improvement of reproduced images can be perceived by human vision. This arithmetic can be the preferred one to compress and map wide color gamut. The direct and practical significance of the research achievements about this issue is that the wide gamut images taken Pointer color gamut as target gamut broadcasted by TV center according to ITU-R BT.1361(the extended color gamut part in China's GY/T 155-2000 is enacted referring to this international standard) can be reproduce with better visual perception on current small gamut TV displays after proper gamut mapping.