Preserving edge structures is a critical issue for reconstructing a high-resolution image from a low-resolution image. In previous works, there is a directional filtering and data fusion(DFDF) image interpolation method[2] preserving edge structures of original image with fast processing speed. But this method has a weakness that it cannot reconstruct line edges properly. In this paper, we propose a modified DFDF method that can preserve line edges effectively. In order to take line edges into account without degrading the performance of the existing DFDF, we introduce a modified filter coefficient by using background value estimation of input pixel blocks. The experimental results show that the proposed method outperforms the DFDF method in terms of PSNR and subjective visual quality.