ztv.py 文件源码

def get_auto_clim_values(self, *args):
        """
        Set min/max of display to n_sigma_below and n_sigma_above background

        'cheat' for speed by sampling only a subset of pts
        """
        finite_mask = np.isfinite(self.display_image)
        n_finite_pts = finite_mask.sum()
        if n_finite_pts > 0:
            n_pts = 1000
            # sample ALL points unless the sampled points will be reasonably nicely distributed.  e.g.
            # n_pts=1000, n_finite_pts=1999 -> all samples would be clumped in one half.
            # factor of 5* means that the 'missing' unsampled clump at the end is <=20% of total pts, which seems reasonable
            if n_finite_pts < (5*n_pts):  
                robust_mean, robust_median, robust_stdev = sigma_clipped_stats(self.display_image[finite_mask])
            else:
                stepsize = n_finite_pts/n_pts
                robust_mean, robust_median, robust_stdev = sigma_clipped_stats(self.display_image[finite_mask].ravel()[0::stepsize])
            n_sigma_below = 1.0
            n_sigma_above = 6.
            return (robust_mean - n_sigma_below * robust_stdev, robust_mean + n_sigma_above * robust_stdev)
        else:
            return (0., 0.)  # no valid pixels