Two-dimensional representations of the DANN embeddings (a representative model with S/N ∼ 40) colour-coded by the source domain classes, and various line ratios (which are either the input features themselves or a combination of input features), shown as the titles of each panel. The colourbar goes from blue (low) to yellow (high) and in each panel is normalised to the 2nd and 98th percentiles of the quantity. The arrow emerging from the origin shows the direction of steepest increase in the colour-coded quantity, measured clockwise from the positive x-axis.