Fit to the median profile plotted against (y-axis) the median values calculated separately for each filament profile (x-axis). The gray solid line represents a relation of y = x. Quality flags are represented by a star, square, circle, and triangle, in order of decreasing quality. The fit to the entire field, regardless of quality flag, is shown by an asterisk. The dashed lines represent upper and lower bounds to the fits. In frame 1, the color of the line corresponds to the field.