Film Match Spectra

Kodak publishes a surprising amount of information in its datasheets about how the stocks behave across the pipeline. Spectral sensitivities, characteristic curves, dye behavior, for both negatives and print stocks...all of that gives us a way to build a grounded model of the photochemical system. By calculating exactly how a digital sensors and actual film stocks respond to light at every single wavelength across the visible spectrum, we completely recreated the photochemical pipeline in a digital simulation.

Instead of only pointing a film camera and a digital camera at a scene, measuring the result, and treating the film system like a black box, I simulated the stimuli itself, let film and digital observe that same stimuli, and then use ColourMatch to match the digital camera response to the film response.

That’s the core idea:

1. build a spectral stimuli from the light source and the reflectance of an object

2. let a film system respond to a variety of stimuli

3. let a digital camera respond to that same variety of stimuli

4. use a powerful color matching algorithm like ColourMatch to map one to the other

It is being built from the way light interacts with the world, the way Kodak negative and print stocks respond to that light, and the way a digital camera sees the same thing.

To me, that is where this gets really cool, because we are modeling how the medium itself sees the world.

Once you have a spectral simulation pipeline, you are no longer limited in the same way you are with purely measured data.

You can:

- generate huge amounts of stimuli inside the simulation

- target the types of spectra you care about most

- swap the illuminant and see what changes

- test a tungsten build against daylight

- try a specific LED source

- compare Vision2 and Vision3 more directly

- and even explore stocks that are not realistically available anymore, like Kodachrome