Images were repeated in all tested conditions after lung injury induction by acid aspiration and are shown in (A) at positive end-expiratory pressure (PEEP) 5 cm H₂O and in (B) at PEEP 10 cm H₂O. The left panels show the target supine images, warped-prone image (shown inverted), and original (nonwarped) prone image. The middle panel shows the change of density in Hounsfield Units (ΔHU) and Jacobian maps side by side, with the corresponding cumulative frequency distribution in the right panels.