Fig. 3

For each SEER standard reference map design, four different modes can provide improved contrast during visualization. As a reference we use the gradient descent map applied on a Simulated Hyperspectral Test Chart (SHTC). a Standard mode is the standard map reference. It covers the entire phasor plot circle, centering on the origin and anchoring on the circumference. The color palette is constant across samples, simplifying spectral comparisons between datasets. b Scaled mode adapts the gradient descent map range to the values of the dataset, effectively performing a linear contrast stretching. In this process the extremities of the map are scaled to wrap around the phasor representation of the viewed dataset, resulting in the largest shift in the color palette for the phase and modulation range in a dataset. c Max morph mode shifts the map center to the maximum of the phasor histogram. The boundaries of the reference map are kept anchored to the phasor circle, while the colors inside the plot are warped. The maximum of the phasor plot represents the most frequent spectrum in the dataset. This visualization modality remaps the color palette with respect to the most recurring spectrum, allowing insights on the distribution of spectra inside the sample. d Mass morph mode, instead, uses the histogram counts to calculate a weighted average of the phasor coordinates and uses this color-frequency center of mass as a new center for the SEER map. The color palette now maximizes the palette color differences between spectra in the sample.