An adaptive coupled bidirectional flow process was presenfed

where an inverse diffusion was performed to enhance edges along the normal directions to the isophote lines（edges）

while a normal diffusion was done to remove ar-tifacts（“jaggies”） along the tangent directions.The two converse diffusion forces were splitted into a coupled form to stop the cancellation between each other.In order to preserve image features

the nonlinear diffusion coefficients were locally adjusted according to the directional derivatives of the image.And then the above process was applied to image interpolation.Experimental results demonstrate that our interpolation algorithm substantially improves the subjective quality of the interpolated images over conventional interpolations and relative equations.