Snapshot of all the four cases under study. From top to bottom: September 6, 2011; March 7, 2012; June 14, 2012; and March 8, 2019. The shown time instant corresponds to when the dimming is close to its maximum extension. Left column: original SDO/AIA image. Middle left column: LBR image corresponding to the SDO/AIA direct image. Middle right column: original STEREO/EUVI image of the Sun. Right column: LBR image corresponding to the original STEREO/EUVI. The colorbar of the LBR images is based on the interval from −2 to 2, highlighting both decreases (red) and increases (blue) in emission. Red asterisks indicate flare coordinates for every event.