© 2026 Bryan R. Hinton This is not AI art. No generative model painted, styled, or hallucinated anything into this scene. A spectral reconstruction model expands a single linear raw capture into a dense spectral cube spanning the visible and near-infrared. From that cube, a Spectral Angle Mapper (SAM) compares every pixel against a library of known spectra. Here is exactly what the spectral angle computes: For every pixel in the scene, we take its reconstructed spectrum \( \mathbf{s} \) (its reflectance across many narrow wavelength bands). We compare that pixel spectrum against a library of known reference material spectra \( \mathbf{r} \). The spectral angle \( \theta \) is the angular distance between these two vectors in \( n \)-dimensional band-space: \[ \theta(\mathbf{s}, \mathbf{r}) = \arccos\!\left( \frac{\mathbf{s} \cdot \mathbf{r}}{\lVert \mathbf{s} \rVert \, \lVert \mathbf{r} \rVert} \ri...