General scale interpolation based on fine-grained isophote model with consistency constraint

In this paper, we propose a fine-grained isophote model with consistency constraint to characterize the piecewise-stationarity of image signals. According to this model, we present a novel interpolation algorithm. In this model, the displacement coefficient is used to model the isophote. Then fine-grained pixel intensity information is introduced to correct the displacement calculation and make the isophote estimation more robust. In order to handle the piecewise-stationarity, we force the isophote direction consistent in the local window when an interpolated line is piecewise-stationary. The proposed algorithm can accommodate the general scale enlargement. Experimental results demonstrate that the proposed approach achieves better performances in both objective and subjective quality assessment.