<P> A color film is made up of many different layers that work together to create the color image . Color negative films provide three main color layers: the blue record, green record, and red record; each made up of two separate layers containing silver halide crystals and dye - couplers . A cross-sectional representation of a piece of developed color negative film is shown in the figure at the right . Each layer of the film is so thin that the composite of all layers, in addition to the triacetate base and antihalation backing, is less than 0.0003" (8 μm) thick . </P> <P> The three color records are stacked as shown at right, with a UV filter on top to keep the non-visible ultraviolet radiation from exposing the silver - halide crystals, which are naturally sensitive to UV light . Next are the fast and slow blue - sensitive layers, which, when developed, form the latent image . When the exposed silver - halide crystal is developed, it is coupled with a dye grain of its complementary color . This forms a dye "cloud" (like a drop of water on a paper towel) and is limited in its growth by development - inhibitor - releasing (DIR) couplers, which also serve to refine the sharpness of the processed image by limiting the size of the dye clouds . The dye clouds formed in the blue layer are actually yellow (the opposite or complementary color to blue). There are two layers to each color; a "fast" and a "slow ." The fast layer features larger grains that are more sensitive to light than the slow layer, which has finer grain and is less sensitive to light . Silver - halide crystals are naturally sensitive to blue light, so the blue layers are on the top of the film and they are followed immediately by a yellow filter, which stops any more blue light from passing through to the green and red layers and biasing those crystals with extra blue exposure . Next are the red - sensitive record (which forms cyan dyes when developed); and, at the bottom, the green - sensitive record, which forms magenta dyes when developed . Each color is separated by a gelatin layer that prevents silver development in one record from causing unwanted dye formation in another . On the back of the film base is an anti-halation layer that absorbs light which would otherwise be weakly reflected back through the film by that surface and create halos of light around bright features in the image . In color film, this backing is "rem - jet", a black - pigmented, non-gelatin layer which is removed in the developing process . </P> <P> Eastman Kodak manufactures film in 54 - inch (1,372 mm) wide rolls . These rolls are then slit into various sizes (70 mm, 65 mm, 35 mm, 16 mm) as needed . </P> <P> Motion picture film, primarily because of the rem - jet backing, requires different processing than standard C - 41 process color film . The process necessary is ECN - 2, which has an initial step using an alkaline bath to remove the backing layer . There are also minor differences in the remainder of the process . If motion picture negative is run through a standard C - 41 color film developer bath, the rem - jet backing partially dissolves and destroys the integrity of the developer and, potentially, ruins the film . </P>

When was the first colour video camera invented