The Work and Methodology
2 STRIP AND 3 STRIP TECHNICOLOR LOOK:
Martin Scorsese wished this film to represent the state of the art color technology of the day in which the story was taking place. From 1927-1934 both in Hollywood and the chronology of this story Two Strip Technicolor was the only color process available.
In short, natural skin tone was achieved by filming two black and white strips of film (with a red and green filter on the lens) and later adding Yellow dye to the resulting Cyan and Magenta printing matrices. The yellow dye makes up for the lack of yellow color found in skin tone pigment but ultimately can not reproduce yellow or any shade or variation of blue (as a result of the missing blue layer.) The resulting matrices appear orange and a warmer version of cyan more than the normal magenta and cyan found in the later three color process. This look creates an odd but pleasing hand-painted look where faces appear normal and green takes on a blue-green quality while the sky and all things blue appear cyan. (See photographs on page 10)
The post 1934 color treatment became the 3 Strip Technicolor look created (see photographs on page 10) by imitating the quality the red, green and blue layers have when originally photographed in black and white with the very discerning Technicolor deep red, green and blue filters on the camera lens. Our less discerning modern monopack films create crosstalk between the layers and cannot totally reproduce the pure primary colors the less flexible Technicolor method could afford. By digitally re-filtering the layers using a version of a primary color matte it helped remove this inherent crosstalk. If you picture a density matte of the blue areas of the film only (grey in the blue area and white in the non blue) then multiplied it with the red and green layers the blue areas of those layers would get darker. The darker that area is, the less red and green colors are allowed to be printed through. For example, a blue sky becomes bluer if there is more density in the sky area of the red and green layers allowing less of those colors to print through.
This multilayered matte strategy was constructed in After Effects and produced a generic "Technicolor Filter" that could be applied to any image including a multicolored chip chart. This chip chart produced the basis of a 3D LUT by comparing each color before the "Technicolor filter" and after. This LUT was produced by Josh Pines of Technique (Technicolor's Digital Intermediate Division) and was used after the Da Vinci color corrector and before the Christie 2K projector to view the results in real time. This LUT was later converted and baked into the resulting Cineon files and filmed out. The hardware and software versions of the LUT were identical and every frame of the film was treated based on chronology with either the 2 or 3 Strip look.