On Compatible Transmission Of Four-primary-color WCG Video Image

In recent years,wide color gamut video image technology has made great progress,greatly improving color gamut coverage by adopting three-primary-color imaging and display technologies with more saturated three-primary colors and multi-primary-color imaging and display technologies with multi-primary-color backlights or multi-primary-color filter arrays.In this paper,the three-primary-color and multi-primary-color imaging and display technologies of the extended color gamut have been extensively studied and analyzed.To overcome the problem that images captured by the current imaging system with the multi-primary-color image sensor cannot be transmitted under the three-primary-color channels,as well as the wide color gamut display system does not have multi-primary-color image contents,this paper designs and implements the wide color gamut four-primary-color video image color codec scheme compatible with the three-primary-color standard and verifies the applicability to the mainstream video image coding standards.The research works carried out in this thesis are as follows:1.Firstly,the four-primary-color video image compatible color codec scheme based on quadrilateral decomposition is designed,which solves the problem of additionally transmitting the fourth primary-color chrominance component resulting in the huge increase in data volume.The quadrilateral composed of the four-primary colors is decomposed into two triangles,and the composite colors located in each of the triangles can be uniquely expressed by the three-primary colors.2.Two color representation methods for video images of four-primary colors compatible with YUV format are introduced.In an image,the pixel area that can be mixed by the common three-primary colors,i.e.red(R),green(G),and blue(B)(RGB)is encoded as a luminance signal and two color difference signals(YUV)using the standard color coding equations.The pixel area that cannot be mixed by RGB three-primary colors but can be mixed by G,B and the fourth primary color X(XGB)is encoded into a pseudo YUV format by using different color coding methods.3.The blind identification of the source of YUV signals is implemented,that is,whether it originates from the RGB three-primary colors or the XGB three-primary colors.In this paper,the general RGB decoding equation is used to decode the YUV signals.If the YUV signals are composed of XGB signals,one or more primary-color values decoded will be negative,and this is not the case with YUV signals consisting of RGB signals.In this way,the blindly identification of the source of the YUV signals is realized,thereby achieving the purpose of correctly transmitting and displaying the four-primary-color video images.4.The applicability of the four-primary-color video image color representation scheme to the mainstream video image compression algorithms as JPEG and HEVC/H.265 based on the Main-RExt framework is verified.The experimental results show that the four-primary-color video image color codec scheme proposed in this paper can correctly represent and transmit the four-primary-color image contents based on the three-primary-color channels,the coding efficiency is effectively improved and the image compression performance is improved in terms of image compression rate,peak signal-to-noise ratio,structural similarity index and run time.