Abstract：Considering the anisotropic characteristics of screen content, satisfactory coding efficiency cannot be achieved when screen content is coded only by traditional image/video coding tools. A new Dual-coder Mixed Chroma-sampling-rate (DMC) technique is proposed for full-chroma (YUV4:4:4) screen content coding by adding a dictionary-entropy based coder which extracted from Lempel-Ziv-Markov chain Algorithm (LZMA) to existing High Efficiency Video Coding (HEVC) SDK tools for better coding efficiency of discontinues-tone portion of screen content. Two coders are seamlessly unified and the optimal coder is selected adaptively macroblock-by-macroblock to fit the characteristics of the macroblock content. A mixed chroma-sample-rate method is also proposed for reducing distortions to convert YUV4:4:4 to YUV4:2:0. Coding experimental results show that DMC coding can achieve much higher PSNR than the current HEVC. There are also obvious improvements on the subjective visual quality differences between them.
2013, Vol. 35 
