One of the most contrasting colour effects you can get in photography is by using infrared. An easy way to understand near-infrared light is to think of it as the colour of the rainbow next to red, a colour that is invisible to the human eye. But near-infrared is not the same as thermal imaging.
Because everyday objects reflect infrared in proportions that differ sharply from that of visible light, the tonal relationships are wildly unexpected. Such near-infrared techniques used in photography give subjects an exotic, antique look. Green vegetation becomes white, whereas human skin becomes pale and ghostly. The resulting images look alien.
Colour infrared images use filters 590 nm – 720 nm (in camera or on the lens) which is close to the visible light spectrum (400 – 600 nm). Often some “bleed” spectrum visible light spectrum interferes with the colour infrared imagery.
Samples of my colour infrared images are shown below.