Another possibility for visualising multi-temporal data relies
on the additive synthesis of colours by the eye. The human eye interprets
the superimposition of the primary colours (red, green, and blue)
as new colours covering all the colours of the rainbow. If we superimpose
an image acquired on one date and displayed in red on an image acquired
on another date and displayed in green, the resulting image will
contain colours ranging from black to yellow, with all the hues
of green and red in between.