Color-color diagrams based on the use of the five optical and NIR colors adopted as features in this work: u − B, B − r, r − i, i − z, and z − y. The smaller gray dots represent the main sample. The sources in the LS are shown as: gray stars (stars), green diamonds (inactive galaxies), and empty circles (AGN). The RF5 AGN candidates are shown as filled circles. All AGN are color-coded according to their redshift, based on the scale shown on the right vertical axis.