| """Image quality gate. Quantifies blur / exposure / resolution and decides whether the |
| image is good enough to judge. Abstaining on unusable images is a feature: it prevents |
| confident-but-wrong outputs under bad conditions. Uses numpy + Pillow only. |
| """ |
|
|
| from __future__ import annotations |
|
|
| from pydantic import BaseModel |
|
|
|
|
| class QualityReport(BaseModel): |
| ok: bool |
| reason: str |
| blur: float |
| brightness: float |
| min_side: int |
|
|
|
|
| def assess( |
| image_path: str, |
| *, |
| min_side: int = 64, |
| blur_threshold: float = 12.0, |
| dark: float = 15.0, |
| bright: float = 245.0, |
| ) -> QualityReport: |
| import numpy as np |
| from PIL import Image |
|
|
| gray = Image.open(image_path).convert("L") |
| w, h = gray.size |
| side = min(w, h) |
| arr = np.asarray(gray, dtype="float64") |
|
|
| brightness = float(arr.mean()) |
| |
| lap = ( |
| -4.0 * arr |
| + np.roll(arr, 1, 0) |
| + np.roll(arr, -1, 0) |
| + np.roll(arr, 1, 1) |
| + np.roll(arr, -1, 1) |
| ) |
| blur = float(lap[1:-1, 1:-1].var()) if side > 2 else 0.0 |
|
|
| if side < min_side: |
| return QualityReport( |
| ok=False, |
| reason="resolution too low", |
| blur=blur, |
| brightness=brightness, |
| min_side=side, |
| ) |
| if brightness < dark: |
| return QualityReport( |
| ok=False, reason="too dark", blur=blur, brightness=brightness, min_side=side |
| ) |
| if brightness > bright: |
| return QualityReport( |
| ok=False, |
| reason="overexposed", |
| blur=blur, |
| brightness=brightness, |
| min_side=side, |
| ) |
| if blur < blur_threshold: |
| return QualityReport( |
| ok=False, |
| reason="too blurry / no detail", |
| blur=blur, |
| brightness=brightness, |
| min_side=side, |
| ) |
| return QualityReport( |
| ok=True, reason="ok", blur=blur, brightness=brightness, min_side=side |
| ) |
|
|
