The setup is deceptively simple: a tripod, three colour-separation filters (red, green, blue), and the patience to let the world walk through the frame three times without moving the camera.
The trichrome process dates back to the 1850s and 60s, when photographers first discovered that full colour could be reconstructed from three separate exposures made through coloured filters. The catch was that nothing in the scene could move between exposures — not a leaf, not a shadow.
Inverting the premise
My approach inverts that constraint entirely. I set the camera on a tripod in a busy location — a market, a sidewalk, a transit stop — and make three sequential exposures, one through each filter. Everything stationary in the scene combines cleanly into a full-colour image. Everything that moved between exposures leaves a colour-separated trace.
The result is a full-colour photograph where moving subjects dissolve into ghost traces — hidden in plain sight until you look through the filter that captured them.
A person walking through the frame during the red exposure might appear as a faint warm ghost at one position. If they moved during the green exposure, a green trace appears slightly displaced. The blue exposure catches them somewhere else entirely. In the composite, they are present but invisible — dissolved into the colour information of the scene.
The reveal
What makes this compelling is what happens when you isolate individual channels. The red filter image is a black-and-white photograph of exactly what was present during that exposure alone. The green and blue images are the same — each a separate moment in time, just seconds apart, captured within the same frame.
On the website, the R / G / B buttons do exactly this: they apply a mathematical colour channel extraction to the composite image, effectively "rewinding" to each individual exposure and showing you the subjects that were there — the people, the cyclists, the vehicles — hiding in the finished photograph.