Technicolor 3 Strip

Technicolor is a colour film printing process invented in 1916. It was the most widely used colour process in Hollywood from 1922 to 1952 and celebrated for its saturated levels of colour. It was used most commonly for filming musicals such as The Wizard of Oz and Singin' in the Rain and used for Disney’s animated classics such as Snow White and the Seven Dwarfs and Fantasia.

"Technicolor" is the trademark for a series of colour motion picture processes pioneered by Technicolor Motion Picture Corporation (a subsidiary of Technicolor, Inc.), now a division of Technicolor SA. The process involved capturing the individual colour components red, green and blue on three individual black and white negatives.

Technicolor 3 Strip Camera & Prism Assembly Diagram

Above is a 3-strip Technicolor camera from the 1930s. Two strips of 35 mm black and white film negative, one sensitive to blue light and the other to red light, ran together through an aperture behind a magenta filter, which allowed blue and red light to pass through. A third film strip of black and white film negative ran through a separate aperture, behind a green filter. The two apertures were positioned at 90 degrees to each other, and a gold-flecked mirror positioned at 45 degrees behind the lens allowed 1/3 of the incoming light to go directly through to the green-filtered aperture, and reflected the remaining light to the magenta-filtered aperture. Because of this division of light between three film strips, Technicolor photography required much more lighting than black and white photography.

Three black and white films are transported through the prism assembly. The light coming through the camera lens, (A), travels to the double prism beam splitter, (B) and a portion of the light passes straight to the film behind the green filter, (C). The balance of the light is reflected by the gold flecked surface (later changed to silver) and passes through a magenta filter, (D) that removes the green light and transmits only red and blue. The red and blue films, (F) are bipacked emulsion-to-emulsion. Since this light must pass through the base of the blue film, the images recorded on the blue and red films are slightly less sharp than the green element, but the difference is minimal. The blue film had a red orange dye coating on top of its emulsion which acted as a filter to prevent any blue light from reaching the red element film, which was sensitive to both red and blue light. During development the filtering dyes were washed from the black and white negative. Note that the red and green films were panchromatic, (sensitive to all colours in the visible spectrum), while the blue film was orthochromatic, (sensitive to blue, green and violet light, but not to red).


A number of slight variations to the printing of Technicolor films were used over the years. Described below is the typical method used through 1945. The images are taken from African Queen which used the Technicolor process. (The director of photography was Jack Cardiff, whom I had the pleasure of meeting when he officially opened Dragon DI in 2005.)


Three negatives from Technicolor camera



Receiver Film

The production of prints began with a “blank” receiver film which was a black and white stock coated with chemicals called dye mordants. The function of a mordant is to attract and hold colour dyes so they do not spread or bleed during the high pressure dye application. The “blank” also held the soundtrack, black frame lines, and usually a 50% density copy of the green component exposed to it, (although sometimes the blue component was used.)

The efforts involved in creating the "blank receiver" offered several benefits over other methods of producing prints. Being a black and white stock, the soundtrack could be optimized for the best reproduction, which was not possible with dye soundtracks such as were used on Cinecolor and other inferior processes. Technicolor's sound track was even considered superior to that of conventional black and white films in which variations in producing the picture would affect the nature of the sound. Die hard Cinephiles of Warner Bros. and MGM films can distinguish that each studio's product had a distinctive look and sound. The black framelines covered the edges of the printed dye images so that variations in the actual component size were not visible. And the 50% black and white "key" image improved contrast and increased the apparent sharpness of the photography.


Printing Matrices – Step 1

The three printing matrices begin life looking like conventional black and white films with differing tones because of their exposure to red, green or blue. The negatives are printed to the matrix stock and the silver image is washed from the resulting print. This leaves a gelatin "topographical map" impression of the colour content in each matrix. The gelatin is transparent and the image is nearly invisible.

Printing Matrices – Step 2

Each matrix is coated with a complimentary colour dye. The red matrix using cyan, the green magenta and the blue using yellow. One at a time the matrices were brought into contact under high pressure, with the prepared receiver film and the dye is transferred to the receiver. With each successive step the colour image takes form on the final print. (The depth of the gelatin impression is exaggerated for the sake of illustration.)


The final print requires an accuracy for registration
of 8/10,000 of an inch or better



Recreating & Restoring Technicolor 3 Strip Today

By the late 60s, the dye-transfer process eventually fell out of favour because the process was too slow in turning out large print runs. Growing number of screens worldwide increased print runs exponentially. No one argued dye-transfer printing yielded superior colour printing, however the number of high speed prints that could be struck in labs was limited to Technicolor and cost more. The last American film released before Technicolor closed their dye plant was The Godfather, Part II (1974).

In 1975, the US dye transfer plant was closed and sadly Technicolor became an Eastman-only processor. In 1977, the final dye-transfer printer left in Rome was used by Dario Argento to make prints for his horror film Suspiria and finally in 1980, the Italian Technicolor plant ceased printing dye transfers.

Reintroduction of the Dye Transfer Process

In 1997, Technicolor reintroduced the dye transfer process to general film production. A refined version of the printing process of the 1960s and 1970s, it was used on a limited basis in the restorations of films such as The Wizard of Oz, Rear Window, Funny Girl, and Apocalypse Now Redux.

After its reintroduction, the dye transfer process was used in several big-budget, modern Hollywood productions. These included Bulworth, Pearl Harbor, and Toy Story. The distinct "look" this process achieves, often sought after by filmmakers looking to re-create the period of time at which Technicolor was at its most prominent, is difficult to obtain through conventional, high-speed printing methods and is one explanation for the enduring demand and credibility of the process. Finally though, the dye-transfer process was discontinued by Technicolor in 2002 after the purchase of the company by Thomson, which in 2010 changed its name to Technicolor SA.


Restoration Today

Images courtesy of Genevieve (1953)

Without the full Technicolor matrices, which were stable and do not degrade unlike older film stocks, it is difficult and costly to restore a full feature. Most of the matrices unfortunately were destroyed to save space; in fact I have never seen a full collection of them, only individual reels. Usually only the original negatives remain. It is expensive to restore a 3 strip Technicolor film because of the exhausting scanning needed, having to scan each separate negative and recombine them into a singular negative for today’s printing process. Every restoration in effect scans and stores the equivalent of 3 full length features to create a final print. This is why it is expensive and a rather laborious procedure and ultimately why only major films are restored to their original glory, which will hopefully recoup the costs involved.


3 strip combiner demonstration


After initial scanning you have three individual channel representations. Which are treated individually to remove any colour bias, these are then combined to create a colour image. The resulting film can then be graded normally, depending on how the ‘interpretation’ or look of the final project should be. Registration issues can be addressed on a scene by scene basis which were a big issue in the original printing stages, as you were obviously at the whim of any jitter or weave on the mechanical sprockets, which may be worn.


3 stills from Genevieve with registration issues

Roll over the images to see the digitally registered versions, notice the image is much sharper when registered correctly


Comparison - note the red edge along the left hand edge of the face and how soft the intricate clothing appears

Another problem combining the negatives is the extra grain added to the image, which would not have been in the matrices. You are in effect adding three times as much grain, which needs to be treated or removed. Unfortunately over dialling the grain removal can also be detrimental to the image and a happy medium has to be found scene to scene, stock to stock.


Before (left) & After (right) re-registered Technicolor 3 Strip scene from Genevieve