This paper presents an extensive evaluation of a novel intensity-based image co-registration method called luminance transformed differences (LTD) which is compared with current alternatives. The proposed method suggests the use of the luminance transform operation (LTO) to reduce luminance differences between images that may well affect image registration accuracy. Registration is implemented in a block-based fashion in order to achieve a non-rigid transformation at a sub-pixel accuracy level. Sample images from different sensors, exhibiting various geometric distortions, are registered to test the various intensity-based image registration alternatives. LTD is found to outperform other methods; its high accuracy can be achieved even using small searching blocks which substantially reduce the computational cost.