So what are the necessary conditions of a color film?

- A blue sensitive emulsion
- A blue-green sensitive emulsion
- A blue-red sensitive emulsion
Stacked in this order; blue sensitive layer facing lens.

- Dye layer
Yellow layer beneath the first blue-sensitive layer, cuts out the blue so the blue-green sensitive emulsion only records the green, same with the blue-red sensitive layer.

- A means to turn the silver-halide images to color.
The last condition has been accomplished two ways in recent history. The chromogenic (C-41/E6) method and the Kodachrome method. Using dye-couplers incorporated in the emulsion that are activated by the developer and controlled diffusion of dyes, respectively.

There are other methods of producing color from silver halide images, such as chemical toning. Several books exist that cover these methods extensively.

Emulsion makers, where do your sensitivities lie? Could you, if charged, create the necessary sensitivities?

The yellow dye later must be eradicated during processing, right?