Bleach Bypass

Skipping the bleach step in film processing leaves silver in the print on top of the dyes. A black and white image and a colour image end up in the same frame, so colour drops and contrast climbs at once.

It reads as harsh and recorded. War, crime and anything meant to feel survived rather than lit borrowed the look, and it outlived the chemistry that made it.

Two things move together. Saturation comes down toward grey, and contrast goes up until the blacks crush and the highlights push toward white.

Highlights take on a metallic quality, because the retained silver is grey rather than coloured. Asking for hard, slightly cold highlights gets closer than asking for brightness.

Grain usually comes with it. The process raised apparent grain, so a clean digital frame with its colour drained can look wrong in a way that a little texture fixes.

Use it on combat, on crime, on industrial settings, and on anything that should feel recorded rather than composed.

Skip it on skin you want to flatter. It is unkind to faces, which is most of the reason it works where it works.

Plain desaturation lowers the colour and leaves the tonal range alone, so the picture goes grey and stays soft.

Bleach bypass does both at once. Look at the blacks. Open and grey means desaturation. Crushed to nothing under hard bright highlights means bleach bypass.

Janusz Kaminski and Steven Spielberg used a silver retention process on the prints of Saving Private Ryan (1998), alongside a narrow shutter angle, so the Omaha Beach sequence carries the density and the stutter of newsreel. Darius Khondji used the same kind of process on Se7en (1995), which is where its grey, heavy rain comes from.

Plain desaturation comes back, grey and soft. Ask for both halves in one sentence: colour drained toward grey, contrast raised hard, blacks crushed.

The second failure is highlights that have simply blown out. Say the bright areas go metallic and keep some detail rather than clipping to flat white.