A very crude rule of thumb might be to divide the square root of the similarity-patch sizes into n, so that the effective sample sizes are 58 and 107 for these patches, respectively. Again, statistical significance falls with lower effective sample size.
To estimate the effectiveness of your analysis, you can divide the square root of the patch sizes by n. This results in an effective sample size of 58 for one set and 107 for another. However, lower effective sample sizes lead to reduced statistical significance.