Point-to-point correlation between radio and X-ray surface brightness (I_R/I_X) for Abell 2142. Upper row shows the regions used to extract the surface brightness measurements. Colourscale is the XMM-Newton surface brightness, with contours showing surface brightness measured by XMM-Newton, MeerKAT and LOFAR from left to right. Boxes are colourised according to whether the surface brightness within is considered a measurement (cyan) or a 2σ limit (blue). Middle and lower rows show the I_R/I_X correlation plane at 1283 MHz (left) and 143 MHz (right) at 60 arcsec resolution. The dashed blue line indicates the 1σ level. Dashed green line shows the best-fit power-law relation and 1σ uncertainty region shown shaded. The slope is indicated in the upper-left corner inset. The lower panels show the results using a common region set where both MeerKAT and LOFAR measure a radio surface brightness of at least 2σ (cyan markers); open datapoints indicate measurements excluded from the fit.