film scanning physics · interactive series
a collection of interactive diagrams for photographers who scan film
Most explanations of film scanning stop at the practical steps — set your exposure, choose a profile, invert in software. This series goes a little bit deeper: into the color layers of film and down into wells of digital sensors that determine why those steps work. They may help figure out what went wrong when sh*t happens ;-) . Each page is a standalone interactive diagram you can explore by dragging a slider or two and observe what changes on the ground. No equations required — but the equations are there if you want them.
How chromogenic development converts colored coupler into dye — and why the unreacted coupler remaining in the emulsion corrects for the shortcomings of real dyes.
Photosites, wells, electron counts, full well capacity, ADC, DN, read noise, shot noise, SNR, quantum efficiency — every term used across the series defined in one place.
The film's characteristic curve translated into raw sensor data. Why equal steps in log exposure produce wildly unequal electron counts — and why the toe and shoulder are your enemy when scanning.
What happens to raw sensor values on their way to a screen. The gap between linear electron counts and perceptual brightness — and why gamma encoding is not optional.
How much of a 14-bit sensor well a color negative actually uses — and where the H&D curve's linear zone lands within that fraction. The wasted headroom and floor explained.
Why negative inversion must happen in linear space — and how a Lightroom import tone curve applied before inversion permanently destroys the toe and shoulder of the original scan.
How colored couplers form the cyan, magenta, and yellow dye clouds during development — and why the orange mask exists, what it absorbs, and how it affects each scanner channel differently.
Why white balance alone cannot correct a scanned negative. The 3×3 matrix that decouples overlapping dye channels — and what happens when it is skipped or applied in the wrong order.
How colored gels and narrowband illuminants shape the spectral power reaching each sensor channel — and whether a filter placed after the film is equivalent to a colored light source.
Read noise, shot noise, and dark current — how they interact with the exponential transmittance curve to set a hard limit on recoverable shadow detail regardless of post-processing.