Examples of reconstructed spectroheliograms from IRIS dense large rasters. Top panel: AR observed on February 4, 2016, at 2800 Å. Middle panel: Same AR image obtained in the intensity integrated over the Mg II k domain (±1.25 Å). The CBs in this AR have been assigned to an EMF region marked with a white contour. Bottom panel: AR on March 24, 2016, at 2800 Å. The white circle indicates a sunspot area, whereas the rectangle is a plage area.