Twelve opacity bins selected for the solar simulation by plotting the opacity strength (or, more precisely, the formation height) against wavelength for all sampled wavelength points. The individual bin elements are indicated by colored symbols. For clarity, we plotted only a subset of the wavelength points considered for the opacity binning procedure. In the background, we included the smoothed histogram of the opacity strength distribution (blue contour). This shows how the majority of λ-points are mostly concentrated close to the continuum-forming layers and only a smaller fraction contributes to lines.