The combination of optical microscan and sub-pixel imaging technology is an effective method to improve the spatial resolution of infrared (IR) detectors. According to analyzing the optical microscan principle and the interpolation reconstruction model,a high resolution imaging algorithm is presented which is based on Lagrange polynomial. Firstly,the proposed algorithm divides the image into different isotropic areas besed on local gradient,and secondly adjusts Lagrange exponents adaptively in these areas. Experimental results show that the proposed algorithm can eliminate image blurring arised from optical microscan effectively,improve spatial resolution of IR imaging system and has good application value.