Distributions of the B-band surface brightness (panel a1), the observed (line-of-sight) H_α velocity (panel b1), and the oxygen abundance (panel c1) across the image of the galaxy UGC 4056 in sky coordinates (pixels). Each characteristic is colour-coded as explained in panel f. The circles show the positions of the kinematic (yellow) and photometric (black) centre of the galaxy. The lines indicate the positions of the corresponding major axis of the galaxy. Panel a2: photometric profile constructed with kinematic angles (the inclination and the position of major axis; circles) and bulge-disc decomposition (line). Panels b2 and c2: rotation velocity and the oxygen abundance as a function of radius, respectively. Panel d: BPT diagram for individual spaxels. The solid (dark) and dashed (red) curves mark the demarcation line between AGNs and H II regions defined by Kauffmann et al. (2003) and Kewley et al. (2001), respectively. The dotted (blue) line is the dividing line between Seyfert galaxies and LINERs defined by Cid Fernandes et al. (2010). Panel e: distribution of spaxels with different types of radiation in the spaxel spectra (H II region-like – blue points, intermediate – red points, and AGN-like – black points) over the image of the galaxy. Panel f: explains the colour-coding of the values of the B-band surface brightness (in units of mag arcsec⁻²), the line-of-sight H_α velocity (in units of km s⁻¹), and the oxygen abundance (in units of dex) used in panels a1, b1, c1. The pixel scale is 0.5 arcsec, the same as the size of the spaxels in the datacube.