Validation Framework

To pass industrial-grade film simulation certification, a measurement standard from molecular scale to perceptual scale must be established. Below is the complete 7-layer verification system, with quantifiable thresholds and Rust-readable test protocols for each layer:

Layer 0: Spectral Fidelity

0.1 Emulsion Spectral Sensitivity $S(\lambda)$

Standard: ISO 5800:2001 / ISO 6846 Measurement Object: Quantum efficiency of Blue/Green/Red sensitive layers to monochromatic light Data Format: 380–780 nm, 5 nm step, 81-dimensional vector Pass Thresholds:

Peak wavelength error $< \pm 5$ nm
Full Width at Half Maximum (FWHM) error $< \pm 15$ nm
Interlayer crosstalk (Blue/Green sensitivity ratio at 480 nm) $< 15%$

Reference Data Source:

#![allow(unused)]
fn main() {
// Kodak Portra 400 Official Sensitivity (Pre-normalization)
const S_BLUE: [f32; 81] = [0.01, 0.03, ..., 0.95, 0.02]; // 380-780nm, 5nm step
const S_GREEN: [f32; 81] = [...];
const S_RED: [f32; 81] = [...];
}

0.2 Dye Spectral Absorption Cross-section $\varepsilon(\lambda)$

Standard: Status A Densitometry Calibration (ISO 5-3) Measurement Object: Absorption spectra of Yellow/Magenta/Cyan dyes at maximum density Pass Thresholds:

Peak absorbance correlation with Kodak patent data $R^2 > 0.995$
Dye overlap (Yellow dye absorbance at 550 nm $< 12%$ of peak)

Layer 1: Exposure Response

1.1 H-D Curve (Hurter-Driffield)

Standard: ISO 6 (B&W) / ISO 5800 (Color) Measurement Object: $\log_{10}(\text{Exposure})$ vs Density $D$ Key Parameters: | Parameter | Symbol | Acceptable Range | Measurement Method | |-----------|--------|------------------|-------------------| | Fog Density | $D_{\min}$ | $0.15 \pm 0.03$ | Unexposed base | | Max Density | $D_{\max}$ | $> 2.8$ | Overexposed by 5 stops | | Contrast | $\gamma$ | $0.55 \pm 0.05$ | Slope of linear region | | Latitude | $L$ | $> 2.8$ stops | $D_{\min}+0.1$ to $D_{\max}-0.1$ |

Rust Verification:

#![allow(unused)]
fn main() {
assert!(hd_curve.gamma >= 0.50 && hd_curve.gamma <= 0.60);
assert!(hd_curve.d_max >= 2.8);
}

1.2 Reciprocity Failure

Standard: ISO 839 Measurement Object: Exposure time $t$ from 1/1000 s to 10 s, keeping $H = I \cdot t$ constant Pass Thresholds:

Density drift $< 0.15$ (1/1000 s to 1 s)
Color shift $\Delta E_{00} < 3.0$ (Layer failure desynchronization at long exposures)

Layer 2: Chemical Coupling (Dye Coupling)

2.1 Coupling Efficiency $\beta$

Standard: Kodak internal process specs (reverse engineerable) Measurement Object: Dye density generated per unit silver density Formula: $D_{\text{dye}} = \beta \cdot (D_{\text{silver}} - D_{\min})$ Pass Thresholds:

Yellow layer $\beta_Y = 1.8 \pm 0.1$
Magenta layer $\beta_M = 2.0 \pm 0.1$ (Higher extinction coefficient for Magenta dye)
Cyan layer $\beta_C = 1.9 \pm 0.1$

2.2 Interlayer Interimage Effects (IIE)

Standard: ISO 4090 Measurement Object: Inhibition/Enhancement of lower layer development by upper layer exposure Test Chart: Red/Green/Blue monochromatic wedges + Neutral gray wedge side-by-side Pass Thresholds:

Development inhibition rate $< 8%$ (High density in upper layer causes density drop in lower layer)
Edge Effect MTF 50% frequency $> 40$ lp/mm

Layer 3: Optical Output

3.1 Status A Density (Print Viewing)

Standard: ISO 5-3 Measurement Object: RGB density measured through Wratten 106/92/88 filters Pass Thresholds:

Neutral Gray $R=G=B \pm 0.05$ (Status A)
Orange Mask Base Color $D_R - D_B = 0.70 \pm 0.05$ (Typical Color Negative Mask)

3.2 Spectral Transmittance $T(\lambda)$

Standard: ISO 5-1 Measurement Object: $T(\lambda) = 10^{-A(\lambda)}$, where $A(\lambda) = \sum C_i \varepsilon_i(\lambda)$ Pass Thresholds:

RMSE with real film transmittance spectra $< 0.02$ (400-700 nm)

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