> as opposed to all the shades of red and blue that are missing because really saturated red and blue primaries are too dim (per unit of energy) to use. Would

> as opposed to all the shades of red and blue that are missing because really saturated red and blue primaries are too dim (per unit of energy) to use. Would another way to put that be, that the chromaticity diagram could keep going southeastward (i.e. the XYZ color-space could have the X and Z activation functions extended leftward and rightward), but due to the frequencies continuing on the spectral line, that area of the diagram would necessarily be made mostly of infrared and ultraviolet frequencies that we can't see?