problem of crop size

Hi, in the README, you said "Reduce the crop size of images. Default crop size is 513. Although any positive integers would work, it is recommended to use values n such that n = output_stride * m + 1 (m is positive integer). For example, 481, 449 for output_stride = 16. ", but I don't understand what are the advantages of setting image size to be output_stride*m+1, could you please explain that?