{
  "artifact_id": "L1-003",
  "layer": "L1",
  "registration_tier": "founder_vetted",
  "principle_number": "003",
  "title": "Coded Aperture Snapshot Spectral Imaging (CASSI)",
  "domain": "Compressive Imaging",
  "sub_domain": "Hyperspectral snapshot",
  "source_file": "B_compressive_imaging/025_cassi.md",
  "E": {
    "description": "Single-shot compressive spectral forward model: a 2D binary coded aperture modulates the scene, a prism disperses each spectral band by a pixel-linear shift, and the detector integrates the dispersed, modulated cube onto a 2D snapshot.",
    "forward_model": "y(x,y) = sum_lambda C(x, y + a*lambda) * f(x, y + a*lambda, lambda) + n(x,y)",
    "world_state_x": "3D hyperspectral radiance cube f in R^{H x W x N_bands}, non-negative, compressible in wavelet/DCT basis",
    "observation_y": "2D sensor snapshot y in R^{H x (W + a*N_bands)} (Poisson+Gaussian read noise)",
    "physical_parameters_theta": [
      "C: binary coded aperture mask (H x W), mask_density in [0.3, 0.7]",
      "a: dispersion slope in pixels per spectral band",
      "alpha: dispersion axis angle (degrees from horizontal)",
      "wavelength range [lambda_min, lambda_max] and N_bands",
      "sensor gain, read noise sigma_read, photon_count peak"
    ]
  },
  "G": {
    "dag": "L.broadcast.spectral -> L.diag.binary -> L.shear.spectral -> int.spectral",
    "vertices": [
      "L.broadcast.spectral",
      "L.diag.binary",
      "L.shear.spectral",
      "int.spectral"
    ],
    "arcs": [
      "L.broadcast.spectral -> L.diag.binary",
      "L.diag.binary -> L.shear.spectral",
      "L.shear.spectral -> int.spectral"
    ],
    "L_DAG": 3.7,
    "n_c": 0
  },
  "W": {
    "existence": true,
    "uniqueness": true,
    "stability": "conditional",
    "condition_number_kappa": 5000,
    "condition_number_effective": 50,
    "condition_number_mismatched": 200,
    "regime": "underdetermined compressive recovery (N_bands:1 compression); binary random mask at 50% fill satisfies RIP-like conditions; recovery unique under spectral sparsity prior; stability governed by mask quality and calibration accuracy."
  },
  "C": {
    "solver_class": "iterative_proximal (GAP-TV, ADMM, PnP) or learned unrolling (HSICNN, MST-L)",
    "convergence_rate_q": 2.0,
    "error_bound": "||f_hat - f||_2 <= C1 * sigma_noise / sqrt(m) + C2 * ||f - f_s||_1 where f_s is best s-sparse approximation; per-channel PSNR scales as 10*log10(1/MSE)",
    "complexity": "O(H * W * N_bands * log(H*W)) per iteration (FFT-based forward/adjoint)"
  },
  "physics_fingerprint": {
    "carrier": "photon",
    "sensing_mechanism": "coded_aperture",
    "integration_axis": "spectral",
    "problem_class": "linear_inverse",
    "noise_model": "shot_poisson",
    "solution_space": "3D_spectral",
    "primitives": [
      "L.broadcast.spectral",
      "L.diag.binary",
      "L.shear.spectral",
      "int.spectral"
    ]
  },
  "difficulty_delta": 3,
  "difficulty_tier": "standard",
  "mismatch_parameters": [
    "disp_a1_error",
    "disp_alpha_error",
    "mask_dx",
    "mask_dy",
    "mask_theta"
  ],
  "error_metric": "PSNR_dB",
  "error_metric_secondary": "SSIM",
  "error_metric_tertiary": "SAM_deg",
  "spec_range": {
    "center_spec": {
      "problem_class": "spectral_reconstruction",
      "forward_operator": "coded_aperture_spectral",
      "input_format": "measurement_only",
      "omega": {
        "H": 256,
        "W": 256,
        "N_bands": 28,
        "mask_density": 0.5,
        "noise_level": 0.01,
        "disp_a1_error": 0.0,
        "disp_alpha_error": 0.0,
        "mask_dx": 0.0,
        "mask_dy": 0.0,
        "mask_theta": 0.0
      },
      "epsilon_fn_center": "28.0 dB PSNR"
    },
    "allowed_forward_operators": [
      "coded_aperture_spectral"
    ],
    "allowed_problem_classes": [
      "spectral_reconstruction",
      "hyperspectral_unmixing"
    ],
    "allowed_omega_dimensions": [
      "H",
      "W",
      "N_bands",
      "mask_density",
      "noise_level",
      "disp_a1_error",
      "disp_alpha_error",
      "mask_dx",
      "mask_dy",
      "mask_theta"
    ],
    "omega_bounds": {
      "H": [
        64,
        2048
      ],
      "W": [
        64,
        2048
      ],
      "N_bands": [
        8,
        128
      ],
      "mask_density": [
        0.3,
        0.7
      ],
      "noise_level": [
        0.001,
        0.1
      ],
      "disp_a1_error": [
        0.0,
        0.05
      ],
      "disp_alpha_error": [
        0.0,
        0.3
      ],
      "mask_dx": [
        0.0,
        1.0
      ],
      "mask_dy": [
        0.0,
        1.0
      ],
      "mask_theta": [
        0.0,
        0.15
      ]
    },
    "epsilon_bounds": {
      "psnr_db": [
        20.0,
        45.0
      ]
    }
  },
  "p1_p10_tests": [
    "PASS",
    "PASS",
    "PASS",
    "PASS",
    "PASS",
    "PASS",
    "PASS",
    "PASS",
    "PASS",
    "PASS"
  ],
  "s1_s4_gates": [
    "PASS",
    "PASS",
    "PASS",
    "PASS"
  ],
  "ipfs_cid": null,
  "verification_status": "triple-verified",
  "verified_by": [
    "agent-physics-verifier",
    "agent-numerics-verifier",
    "agent-cross-domain-verifier"
  ],
  "verification_date": "2026-04-21",
  "display_slug": "cassi"
}