Comparison of observed and simulated O V intensities (I ∝  |φ| ^δL^λ) for the optimum values of δ and λ, for active regions 1 (top), 2 (middle) and 3 (bottom) – see Table 1 for region details. Intensities are in units of erg cm^-2 s^-1 sr^-1. Panels in the left column show the original data, where crosses denote pixels with absolute magnetic flux density φ > 90 Mx cm^-2, used to calculate χ². Pixel size is 4′′ × 4′′. Panels in the right column show the observed O V intensities smoothed with a 5-point running average. The continuous line is an y = x relationship.