1-D dictionary mode for screen content coding

This paper introduces 1-D dictionary mode designed for screen content coding. Two 1-D dictionary modes are designed to improve the coding efficiency for screen content. The first one is called normal dictionary mode, in which a virtual dictionary should be maintained and all the prediction comes from the virtual dictionary. The other one is called reconstruction based dictionary mode, where no virtual dictionary is to be maintained and all the previously reconstructed pixels in the same picture can be used for prediction. Hash based search is designed to find matching for both dictionary modes efficiently. 1-D dictionary mode with variable block sizes are also supported in the proposed scheme. The experimental results show the proposed algorithm achieves about 10% ~ 18.4% bit saving for different coding structures. The bit saving is up to 60% for the proposed method.