关键词: 图像放大, 非线性扩散, 评价体系, 灰度偏移

Abstract: In view of image enlarge，a new method of PM-MF based on nonlinear Partial Differential Equation（PDE） is proposed and applied to image enlarge by considering the two most distinguishable characters：Gradient and smoothing degree.A new set of appraisal system for the qualities of image enlarge is proposed with farther research based on gray scale，ratio of signal to noise，mean square error and absolute value of gradient.From the result it shows that the proposed method precedes linear PDE whatever in keeping edge-based information，excursion of gray scale and the definition of pictures.

Key words: image enlarge, nonlinear diffusion, appraisal system, excursion of gray scale