The Three-Strip Process

Three/Strip™ is not a color filter that pushes hues around until a shot looks vintage. It reproduces the way Technicolor actually made color, which was a subtractive dye process, not an adjustment to a digital image. This page explains what that process did and how the plugin models it, because once you know what the dye is doing, the controls stop being abstract sliders and start being the levers the process itself had.

Color you take away, not color you add

A screen and a Technicolor print build color in opposite directions. Your monitor is additive. It starts black and adds red, green, and blue light until your eye reads the color. A dye print is subtractive. It starts from white light passing through the film and takes color away, each dye absorbing part of the spectrum and letting the rest through. Cyan dye removes red, magenta removes green, yellow removes blue, and what survives is the color you see.

That difference is the whole reason film color behaves the way it does. On a screen, a color gets stronger when you add more light to it. In a dye, a color gets stronger when the dye gets denser, and denser dye blocks more light, so the color darkens as it saturates. That coupling is not a stylistic choice. It is what a dye physically has to do, and it is the single most important thing the plugin holds onto.

The camera saw three times

Three-strip Technicolor recorded a scene as three separate black-and-white negatives at once, one reading red, one green, one blue. Each negative was a plain density record of how much of its color reached the film. There was no color in the negatives themselves, only three grayscale measurements of the same scene.

Color arrived at the print. Each separation was turned into a gelatin matrix, a relief image where the film was thicker where more dye should sit. The matrix for the red record was dyed cyan, the green record magenta, the blue record yellow, and each was pressed in turn onto a blank receiver strip so its dye soaked in. This is imbibition, or dye transfer: three dye images laid down in register on one piece of film. The final print was those three subtractive dyes stacked, which is exactly the cyan-magenta-yellow density model the plugin works in.

The plugin works in density, not in strips

Here is where Three/Strip™ is honest about what it does. It does not literally split your image into three separations and re-transfer them. It reproduces the result of that process directly, in density. Every pixel is converted to optical density per channel, the same quantity a densitometer reads off a print, where density is the log of the reciprocal of the light the dye lets through and rises as the dye blocks more. The look is shaped there, in density space, and then converted back to light at the end by the same physical law a real dye follows, so a denser channel comes back darker.

Two things happen while the image is in density. The first is the characteristic curve, the S-shaped exposure-to-density response every film stock has, which sets how contrast and tone roll off. The second is dye impurity. No real dye is clean: the cyan, magenta, and yellow dyes each absorb some light they were supposed to pass, and that cross-absorption is what gave Technicolor its particular color signature. The plugin builds that cross-absorption from MacAdam’s 1938 published measurements of the actual dye set, applied so that a neutral gray stays perfectly neutral no matter how strong the effect, and only colored areas bend toward the Technicolor primaries. That is why turning the look up mutes and shifts color rather than tinting the whole frame.

The controls, in the model

Once you see the process, the character controls map straight onto it.

Dye Character sets how strongly the dyes borrow from each other, the cross-absorption above. Higher is more period-accurate and, because more crosstalk means more overall density, more muted. This is the control that decides how much like a real Technicolor print the image reads.

Color Softness eases the separation between the three color records toward what the real camera did. The beam-splitter’s taking filters overlapped in the spectrum, so the records were never perfectly clean. At zero you get modern, clean separation; push it up and the color softens toward that older overlap. It starts at zero, because most looks want the cleaner separation.

Dye Depth keys that same crosstalk to how dark the image already is. In a real dye, thicker dye absorbs more of its neighbors’ light, so the effect grows with density. Turn Dye Depth up and the shadows and saturated darks take on more of the look while the highlights stay cleaner, matching how the effect scaled with dye thickness on film.

Richness is the dye-density gain, the subtractive law made adjustable. Push it up and colors intensify by darkening, anchored so no channel can ever come back brighter than it went in, because a dye cannot brighten anything. Pull it down and color contracts toward gray. This is the control that most directly buys saturation the way film bought it, at the cost of luminance.

Saturation trims chroma around the neutral point as a simpler, more familiar overall adjustment, sitting on top of Richness rather than replacing it.

Contrast sets the film characteristic curve, the S-shaped response that decides how tone rolls off. It pivots at mid-grey so your exposure holds while the contrast changes around it. At its default it sits at unity and adds no contrast of its own, so you can run the color model on a faithful tone and let the grade underneath own the contrast.

Black Density deepens the blacks the way the three-strip process did. Technicolor struck a neutral silver key from the green record to weight the shadows, and this control does the same, dropping the low end while holding midtones and skin where they sit. It ships on at a modest amount, because that silver key was part of the look.

Warmth colors the print base toward the golden white real print stock had, applied after the dye model as a gentle per-channel bias rather than a heavy color cast.

Skin Protect eases the crosstalk and the richness expansion on skin tones only, so you can push the look hard everywhere else without dragging faces off their hue or crushing their brightness.

Vibrancy is the quick, combined move: it drives Dye Character and Richness together, so one slider gives you the darkens-as-it-saturates behavior without setting each part by hand.

Two Strip is an earlier, poorer camera

Two-color Technicolor came first, and it was genuinely limited in a way the plugin reproduces rather than smooths over. It recorded only two separations, a red-orange record and a blue-green one, with no independent blue. The plugin’s Two Strip mode does the real thing: it folds your image down to those two records, mixing blue into both of them instead of keeping it, then rebuilds a full-color image from the two dyes that result.

Because the blue never had a channel of its own, it comes back wrong on purpose. Skies and clean blues drift toward teal, and yellows go muddy, exactly the failures two-color Technicolor was known for. This is not Three Strip with the saturation turned down. It is a lossier separation that cannot reach parts of the color volume, which is what makes it read as the older process instead of a weaker version of the newer one.

Where color management fits

The dye model is calibrated for one working space, so the plugin puts your image into that space before the look runs and takes it back out afterward. It reads your footage using the Input Transfer Function and Input Gamut you set, converts to the linear working primaries the model expects, runs the entire density process there, and then encodes the result back into the space it received. The look controls never see your camera’s format. They see a normalized linear image, which is why the same Dye Character or Richness value behaves the same way whether you feed it ARRI, Sony, or a color-managed timeline, as long as Color Management is set correctly. Get those two settings right first, the way Looks & Controls describes, and everything downstream lands where you expect.

The account of subtractive dye color, the three separations, and imbibition dye-transfer printing is standard Technicolor history. The density model, the dye cross-absorption, and its calibration against surviving Technicolor prints are what the plugin itself implements; the cross-absorption is built on MacAdam’s 1938 measurements of the Technicolor dye set.

Next: Put the model to work in Looks & Controls, or start from the top in the Resolve Quick Start.