An example image pair acquired at two different phase angles and a phase angle ratio image that suppresses albedo variations and highlights the slope of the phase curve. Both images in the ratio were acquired on 2013 January 31 with an incidence angle of ∼41°. The top LROC NAC image (M1114255849R) was acquired with an emergence angle of 23° and a phase angle of 19°, capturing the backward-scattering properties of the regolith. The bottom LROC NAC image (M1114241640R) was acquired with an emergence angle of 14° (opposite direction) and a phase angle of 54°, capturing the forward-scattering properties of the regolith. The phase angle ratio is calculated by dividing the low-phase image by the high-phase observation. The distal ejecta in the ratio image are brighter than the background, thus indicating a steep slope of the phase curve in this range. Note that the diagram shows the vectors in the same plane; in reality, there can be slight differences such that the phase angle does not equal the incidence angle ± the emergence angle.