red filter draw rectangles rectangle polygon this is a fudge factor. depending on what you want to do, you set it to 2, 3, 4, whatever. mode 1: a grid[2] mode 2: a grid[2, 2] greyscale image mode 2: alleged centroid (doesn't have to be the real centroid, but when it is, the output will be the variance matrix ; else it won't be a centred moment) when \$1=1, [#moment] calculates the average index of the values in the grid, weighted by the values themselves. If no argument is specified, this is the default value. when \$2=2, [#moment] calculates the average square of index of the values in the grid, weighted by the values themselves. this can be used to compute a variance (covariance) matrix, which in turn can be fed to [#moment_polar] to figure out the standard deviation and the direction of the standard deviation.