Some imaging systems employ detector arrays that are not sufficiently dense to meet the Nyquist criterion during image acquisition. This is particularly true for infrared digital imagers. Therefore

the spatial resolution afforded by the optics can't be fully utilized in such imaging systems. This paper presents a new technique to reconstruct a high resolution image

with reduced aliasing

from a sequence of under sampled rotated and shifted frames of the same object. Firstly

the continuous and digital models of an imaging system are defined to explain image acquisition. Secondly

the image registration algorithm and the ordered subset conjugate gradient (OSCG) reconstruction algorithm are designed. Finally

Simulated experiment results are provided to test our algorithm

and we obtain the image whose resolution is 5 times high than the 25 under sampled frames. The results show that OSCG reconstruction algorithm is robust

rapid convergent

and memory saved.