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Colour Motion Pictures

Seeing & Recreating Colour

Light & Colour Perception

White light is comprised of all of the colours which the human eye is capable of seeing, but the colours in which we see each object depend not only upon the properties of the light which is shining on them but also, at the same time, on the very light-reflecting qualities of the object itself. Hence, an objected illuminated with white light will be seen as being white (o) when it reflects the light of all of the wavelengths in the spectrum in the same proportion and intensity. When it absorbs part of the light of all of the wavelengths, it will be seen as being gray (n) to a greater or lesser degree of brightness depending upon the amount of light it is able to reflect. This same object will be seen in a dominant colour, in red (n), for example, if it reflects solely or mainly the wavelengths of this colour; and it will be seen in black (n) when it absorbs all of the light.

Apart from this, if all of the colours of the spectrum together add up to white light, the colour of any object will also depend upon the colours in the light shining on the object in question. When the light shining on the objects is other than white, it modifies the colour in which they are seen. Hence, for example, two surfaces, which would be seen as being violet and red under white light would both, when illuminated with blue light, are seen as being violet although different shades thereof.

Colour Formation (1) Additive Synthesis

Primary Colours. The adding together of the three colours known as primary additive colours, that is red, green and blue, is sensed by the human eye as being white.

And, as white light is a combination of all colours, any colour can be obtained through different combinations of the three primary colours. Red + blue make magenta/purple, blue + green make cyan (greenish blue) and green + red makes yellow.

Complementary Colours

If all of the three primary colours combined makes white, adding a primary colour, that is, blue, for example, to a complementary colour, for example, yellow (which is made up of green + red) would also make white.

Recreating Colour by Additive Synthesis

Additive synthesis of colour takes place in the human eye proper. It is in the retina that the primary colours are combined; the light spectrum is completed and white is the result.

In industrial printing processes, the colours of the original to be printed are separated photographically into the three primary colours, inserting "mattes" in between dividing the picture into "dots" on the three resulting "negatives". Afterward, the "negatives" are dyed and printed with the pertinent colour such that the "mattes" keep the dots of each colour separate, which the eye will sense separately and will "add up" to synthesize the original being reproduced.

Over many years’ time, in still and motion picture photography, one process after another came out to make recreating colour by means of additive synthesis possible. These processes are based on arranging the emulsions or the filters in mosaics or grids in which each "cell" is "specialized" for capturing one single colour. These systems were always highly complex as regards their operation and failed to meet with success until colour TV systems came out, in which the light signal for each primary colour is processed separately and is routed to the right "cell" within a grid of glow-in-the-dark substances covering the inside of the screens.

Colour Formation (2) Subtractive Synthesis

Using primary colour filters to make colours leads to unexpected results. The combined use of two filters absorbs all the light, "making black". Hence, if a red filter allowing only red to shine through is used in combination with the effect of a green filter, which shuts out red light, the result will be darkness.

Subtractive Primary Colours

As additive complementary colours, the human eye directly perceives magenta, cyan and yellow, but insofar as each one of these colours is comprised of two primary colours, they can also be used to filter out light and to recreate all colours. Therefore, the complementary colours can also be referred to as subtractive primary colours, and any pair of subtractive filters can be used to make the pertinent primary colours.

Hence, a cyan filter allows the wavelengths of green and blue to shine through. If a yellow filter is inserted behind the cyan filter, it will filter out the blue light, given that this colour does not comprise part of its composition, but will allow green light to shine through. If the filter positioned second in line were to be a magenta filter, it would allow blue to shine through. This type of subtractive synthesis will take place with any combination.

Nevertheless, on installing a third subtractive filter, the rest of the light will be absorbed, resulting solely in darkness.

Three Additive Primary Colours = White. Three Subtractive Primary Colours = Black.

Additive synthesis entails the combining of the three primary colours, on building up the brightness of the entire spectrum, being perceived as white. Subtractive synthesis entails the elimination of brightness from the three complementary colours resulting in a colour, which is perceived as black.

Silent Screen Era Colour Printing

Motion pictures first came into being in black and white, yet, from the start, had always aspired to overcome this distortion of the reality it was attempting to make as real-life as possible. Throughout the more than 30 years which colour systems took to be developed, the industry designed different substitutes which met with such great success that nearly all silent films, although they were filmed in black and white, were viewed by moviegoers in colours incorporated into the prints (or into the screening process) in one way or another.

When optical film sound came out, entailing its own individual requirements for the conforming of negatives and the making of prints, this system did away with all of the non-photographic systems used to colour the prints, making black and white taking over the lead for many years in theatres.

Silent Screen Era Film Colouring Systems (This section was prepared with the help of Jennifer Gallego).

During the silent screen era, three basic processes were developed for colouring prints. The first two of these processes used colour without involving it in the photographic process, while in the third process it was the areas on which the picture was filmed that were coloured. Each one of these systems went through several versions, which were often done completely by hand, and combinations of two systems were frequently used, achieving pictures which were not true-to-life, yet were extremely beautiful.

Selective Direct Colouring Procedures

This system, in its different versions, was used throughout the entire silent screen era, although due to its high cost, was generally used for productions short in length. In many cases, uncoloured prints, which were sold more cheaply, were made at the same time.

One or more different colours were applied to the areas selected on each frame to highlight certain images or parts of the frame. These coloured prints are generally readily identifiable, given that the colours cover certain set areas of the image and do not coincide exactly in any two consecutive frames, and the frames usually have some areas, which are not coloured.

Hand-Colouring

Hand colouring was done directly using a brush by coating the area to be coloured on each frame with colour (using water-based or alcohol-based anilines). Now matter how skilled the person doing this hand-colouring might be, the coloured "spot" in each area never coincided exactly with that of the following frame, giving rise to a not too pleasing effect on screening of spots of colour jumping around and constantly changing shape on the screen.

Stencilling

To keep these spots of colour as still as possible and to mechanize this system, a stencil cut out in the shape of the area to be coloured was inserted. These stencils were filled in with colour using a pouncing-bag, placing the stencil on first one frame and then the next until the object, which was being coloured, changed shape.

The Pathè colour process incorporated up to six colours in each frame. The stencils were cut using a blade mounted on a pantograph, a remarkable degree of precision being achieved on tracing around these stencils when enlarging the frame. The anilines were applied with a roller.

Direct Full-Colour Processes. Dyes.

The systems, which became the most widely used were based on applying the anilines over the entire surface of the film stock. These processes, just like the toning processes, required putting the editing sections in order on the negative in keeping with the colouring requirements.

Hand Tinting

The colour was applied to developed prints, the anilines being hand-brushed onto the surface of one side of the stock using a pounce-bag or a polished glass roller.

Dip Dyeing

In this other post-tinting system, the print was immersed, following full processing, into water-based aniline baths and was then dried. This method became widely used, and many laboratories installed facilities for dyeing their prints.

Pre-Tinting or Varnishing

In the twenties, material directly factory-dyed first came on the market for making prints. In this system, the colouring was spread over the stock during the film-manufacturing process, achieving degrees of uniformity and transparency of the dyes, which surpassed those achieved in many laboratories.

When sound was added to motion pictures, some manufacturers continued marketing dyed print material in softer shades in keeping with the needs of uniformity regarding the transparency of the optical sound scanning systems, but sound editing requirements made it impossible for this material to be used.

Chemical Colouring Processes. Toning Processes.

In these systems, it was the photographed image, with its own individual shape and density-related features, which was dyed by means of a chemical replacement process in which the black silver, which the image formed, was replaced by a colouring. Naturally, these processes were done during the laboratory print developing process and required a special editing of the negative.

Metallic Toners

By means of chemical reactions, the silver of the photographed picture will be replaced by other metallic salts (gold, copper, uranium, etc.) of excellent chemical stability-related properties, which were apt for use to replace metallic silver.

Mordant Toners

Organic dyes came in a much wider range of colours, but their use entailed first conditioning the silver emulsion by means of a bleaching bath to remove the silver to be replaced by the dye.

Combining Dyes & Toners

The dye systems were used on the entire frame. On screening, the high-density, opaque (black) areas remained black; the medium densities showed colour in reverse proportion to their density; and the transparent ones showed up as being completely dyed. The toner systems affected solely the picture portions by dying the stock in terms of the photographic density and leaving the transparent areas untouched. These basic differences make it possible for these systems to be combined perfectly well, opening up tremendous prospects for the dramatic use of colour.

Colour Motion Pictures

ADDITIVE SYSTEMS

The problems involved in developing the colour-forming substances necessary for making true colour emulsions led to many different additive synthesis systems apt for use in filmmaking being put on the market.

Black & White Film Systems

Filming was done on black and white stock, the range of wavelengths to strike the emulsion being selected through the use filters.

In some systems, the film was run through at double speed, and the colour was selected using a rotary shutter equipped with a suitable filter for each frame.

In the "Francita" system, the three much smaller-sized frames shared the height of five sprocket holes, and they were filmed and screened using a prism-shaped turret which divided or combined the pictures and inserted the filters.

"Reseau" Colour Systems

The use of true colour emulsions began with these systems, but the problems involved in all cases with regard to creating and adjusting the screened stock to full precision led to their soon falling into disuse.

In the "Dufaycolour" system, the most famous and the only system, which met with industry-wide success, the "reseau-screen" was comprised of 25m strips, the lengthwise strips being red and the crosswise ones green and blue. The "reseau" was adhered to the stock in six consecutive steps and was coated with a black and white emulsion that was protected, in turn, using a flat overcoat to be removed during processing.

The photography was done through the stock, the light shining through the screen and printing the areas of emulsion located beneath the colours contained in the light. After printing, these areas - which were opaque on the negative - would allow the light to shine through the filters, thus recreating the colour.

SUBTRACTIVE SYSTEMS USING BLACK & WHITE NEGATIVES

The first industrial subtractive systems were based on filming on two or three negatives, which were run behind a splitting prism and the suitable filters to achieve the picture for the selected colours. Colour was added to the prints by means of consecutive toning processes or, in the case of Technicolor, through the printing of matrixes.

Technicolor

The Technicolor system, the most famous one of all these systems, came to be used in versions based on two or on three black and white negatives. In the three-negative system, a semi-reflecting prism is used which splits the light striking the object, sending one part to a magenta filter and allowing the rest to flow toward a green filter. Two films (bipack) with their emulsion sides placed up against one another are run behind the magenta filter. The first of these films, the orthochromatic film, will have the blue portion of the picture shone on it; the green picture being shone on the second one, the panchromatic film. After the negatives have been developed, they are printed on films, which will be put through a picture hardening process, followed by a hot bath to remove the remaining emulsion, thus obtaining three matrixes in relief of the printed picture. Each one of these matrixes will be tinted with the complementary colour of the original and stamped in running order on the frame proper of the release print.

Cinefotocolour

Cinefotocolour was one of the last systems invented (1947) prior to negative emulsions for colour becoming used throughout the industry. Two negatives were used in this system, one of which was selected for red-orange and the other for blue . Printing was done in two runs. In the first run, using the red-orange negative, and shining the light through the stock to sensitise solely the layers of emulsion nearest to the stock. After developing (but not fixing) and rinsing the print, a blue toner is applied. The second run entailed putting the side coated with emulsion up against the negative filtering out blue to sensitise the surface of the emulsion. Next, the film would then be re-developed and then fixed, after which a red-orange dye process.

At the end of the process, the colours obtained had to be adjusted by dyeing the print yellow.

SUBTRACTIVE COLOUR NEGATIVE SYSTEMS

In the thirties, subtractive synthesis systems began to be developed to work directly on negative and print stock, these being systems, which have now fully taken over the market.

Colour Analysis

If the light reflecting off an object which includes the primary colours and the complementary colours in addition to black and white is made to shine through primary colour filters, a blue filter will allow the white light, the blue light and the part corresponding to the blue in the magenta or the cyan to shine through. A green filter will do the same with white light, green light and part of the yellow and the cyan light. In the breakdown achieved, each primary colour will form its own colour. The presence or the absence of blue, green and red in the three filtering processes will make black and white; and the combination of the proportions of yellow, magenta and cyan they contain will round out the colours.

Image Formation & Colour Synthesis

Each film manufacturer has set up its own systems, having made changes and improvements for the purpose of getting around the patents held by other manufacturers and of improving their own products to gain an edge on the competition but, generally speaking, with the exception of the order of the layers and the composition of the colour-forming elements having been changed, these systems are all similar.

Diagram of How A Subtractive Synthesis System Works (Based on "Técnica del cine en colour", J.L. Fernández Encinas, 1949. "Agfacolour" System). 1 Original Image

In: Black, white, red, blue, green, yellow, magenta and cyan.

2 Silver Image

Blue colour-sensitive layer containing yellow colour-forming agents + Yellow filter + Green colour-sensitive layer containing the magenta colour-forming agents + Red colour-sensitive layer containing the cyan colour-forming agents.

The white colour sensitises the three layers. The red, blue and green sensitise the areas of their respective layers and, additionally, in the proper proportion, the yellow, magenta and cyan areas. The black area is not sensitised.

3 Image After Colour-Forming Developing Process

Each layer reproduces the image in the pertinent subtractive.

4 Image After Bleaching

The silver image and the yellow filter vanish.

5 Image After Fixing

The image shows up on the negative. Seen on transparency:

--- The light in the area for white is absorbed on passing through yellow, magenta and cyan.

--- That of the area for black is totally transparent.

--- In the areas for red, blue and green, their complementary colours (cyan, yellow and magenta) show up.

--- And in the areas of the complementary colours: magenta and cyan make blue; yellow and cyan make green and yellow and magenta make red.

Printing

The printing process is a process, which is symmetrical to the preceding process, which, just as for black and white photography, can be done using the same emulsion.

The subtractive negative, comprised of black, white, cyan, yellow, magenta, blue, green and red, is printed with the following result:

The light in the area for black does not shot the emulsion.

The light in the area for white shots all three layers, absorbing all of the light.

In the areas of the complementary colours, cyan, yellow and magenta respectively shot the layers sensitised for blue and green (making yellow and magenta), green and red (making magenta and Cyan) and blue and red (making yellow and cyan).

In the areas for blue, green and red, the layers corresponding to these colours are shot, making their complementary colours.

When seen in transparency, the resulting print will be of the same colours and shapes as the camera original photographed.