In digital image forensics, most of the works perform resampling detection by detecting periodicity introduced by the interpolation process. The detection of periodicity is usually done in frequency domain where the resampling rate can be determined simultaneously. But due to frequency aliasing, the resampling rate cannot be totally determined. To solve this problem, an algorithm is proposed which can determine the resampling rate in spatial domain, based on the observation that the redundancy of the image rows (or columns) vary periodically and can be used to determine the resampling rate. As experiments show, all resampling rates can be correctly detected in uncompressed images, and in compressed images the proposed algorithm shows more robustness compared to the prior algorithm.