{
  "default_mode": "document",
  "modes": {
    "none": {
      "description": "No preprocessing (passthrough)",
      "deskew": false,
      "clahe": false,
      "binarize": false,
      "gamma_correction": false,
      "sharpen": false,
      "grayscale": false,
      "target_size": null
    },
    "auto": {
      "description": "Inspect image and apply needed fixes automatically",
      "deskew": true,
      "clahe": "auto",
      "binarize": false,
      "gamma_correction": "auto",
      "sharpen": "auto",
      "grayscale": false,
      "target_size": 1024
    },
    "document": {
      "description": "Deskew + CLAHE contrast enhancement (default for general documents)",
      "deskew": true,
      "clahe": true,
      "binarize": false,
      "gamma_correction": false,
      "sharpen": false,
      "grayscale": false,
      "target_size": 1024,
      "clahe_clip_limit": 2.0,
      "clahe_grid_size": 8
    },
    "low-contrast": {
      "description": "Aggressive CLAHE + gamma correction for faded scans",
      "deskew": true,
      "clahe": true,
      "binarize": false,
      "gamma_correction": true,
      "sharpen": false,
      "grayscale": false,
      "target_size": 1024,
      "clahe_clip_limit": 4.0,
      "gamma_value": 1.5
    },
    "grayscale": {
      "description": "Convert to grayscale + Otsu binarization",
      "deskew": true,
      "clahe": false,
      "binarize": true,
      "gamma_correction": false,
      "sharpen": false,
      "grayscale": true,
      "target_size": 1024
    },
    "high-resolution": {
      "description": "Resize longest side to 1024 with Lanczos + sharpen",
      "deskew": false,
      "clahe": true,
      "binarize": false,
      "gamma_correction": false,
      "sharpen": true,
      "grayscale": false,
      "target_size": 1024
    },
    "table": {
      "description": "Deskew + CLAHE + sharpening for grid lines and table structure",
      "deskew": true,
      "clahe": true,
      "binarize": false,
      "gamma_correction": false,
      "sharpen": true,
      "grayscale": false,
      "target_size": 1024,
      "clahe_clip_limit": 3.0
    },
    "adaptive-binarize": {
      "description": "Detect sideways orientation and apply local Sauvola binarization",
      "deskew": true,
      "clahe": false,
      "binarize": "sauvola",
      "gamma_correction": false,
      "sharpen": false,
      "grayscale": false,
      "target_size": 1024
    },
    "photo-document": {
      "description": "Perspective-correct photographed pages, detect sideways orientation, then enhance contrast and lighting",
      "deskew": false,
      "perspective_correction": true,
      "clahe": true,
      "binarize": false,
      "gamma_correction": true,
      "sharpen": false,
      "grayscale": false,
      "target_size": 1024,
      "clahe_clip_limit": 3.0,
      "gamma_value": 1.3
    }
  },
  "_note": "Preprocessing is always optional. The raw input path remains available for baseline comparison. Applied steps are recorded in output metadata."
}