| from __future__ import annotations |
|
|
| from pathlib import Path |
| from typing import Iterable |
|
|
| from PIL import Image |
| from torchvision import transforms |
|
|
| from .base import FingerprintSample |
|
|
| IMAGE_EXTS = {".jpg", ".jpeg", ".bmp", ".png"} |
|
|
|
|
| class PolyULoader: |
| """Loader for the PolyU Contactless-2D-to-Contact-based Fingerprint Database. |
| |
| Reference: |
| Chenhao Lin, Ajay Kumar, "Matching Contactless and Contact-based |
| Conventional Fingerprint Images for Biometrics Identification," |
| IEEE Transactions on Image Processing, vol. 27, pp. 2008-2021, 2018. |
| |
| Directory layout under ``root_polyu``:: |
| |
| contact-based_fingerprints/ |
| first_session/{X}_{Y}.jpg X=subject_id, Y=impression (1-6) |
| second_session/{X}_{Y}.jpg |
| processed_contactless_2d_fingerprint_images/ |
| first_session/p{X}/p{Y}.bmp |
| second_session/p{X}/p{Y}.bmp |
| |
| The raw contactless images (1400×900, ~3.6 MB) are **not** loaded; the |
| pre-downsampled grayscale versions in |
| ``processed_contactless_2d_fingerprint_images`` are used instead. |
| |
| Metadata fields: |
| identity_id — ``polyu_{X}`` (shared between contact and contactless) |
| finger_id — ``f01`` (one finger per subject in this DB) |
| sensor_id — ``polyu_contact`` | ``polyu_contactless`` |
| dataset — ``polyu`` |
| |
| Cross-modality signal for L_sens: |
| Same (identity_id, finger_id) appears under two sensor_ids, making these |
| the strongest possible cross-sensor anchor pairs for GRL training. |
| """ |
|
|
| SENSOR_CONTACT = "polyu_contact" |
| SENSOR_CONTACTLESS = "polyu_contactless" |
| DATASET = "polyu" |
| SESSIONS = ("first_session", "second_session") |
|
|
| def __init__(self, image_size: int = 224): |
| self.transform = transforms.Compose( |
| [ |
| transforms.Resize((image_size, image_size)), |
| transforms.ToTensor(), |
| ] |
| ) |
|
|
| def discover(self, root_polyu: str) -> list[dict[str, str]]: |
| """Scan the PolyU root directory and return a list of metadata records. |
| |
| Args: |
| root_polyu: Path to the PolyU root folder (the folder containing |
| ``contact-based_fingerprints`` and |
| ``processed_contactless_2d_fingerprint_images``). |
| |
| Returns: |
| List of dicts with keys: image_path, identity_id, finger_id, |
| sensor_id, dataset. |
| """ |
| root = Path(root_polyu) |
| if not root.exists(): |
| raise FileNotFoundError(f"PolyU root not found: {root}") |
|
|
| records: list[dict[str, str]] = [] |
| records.extend(self._scan_contact(root)) |
| records.extend(self._scan_contactless(root)) |
| return records |
|
|
| def iter_samples( |
| self, records: Iterable[dict[str, str]] |
| ) -> Iterable[FingerprintSample]: |
| for rec in records: |
| image = Image.open(rec["image_path"]).convert("L") |
| tensor = self.transform(image) |
| yield { |
| "image": tensor, |
| "identity_id": rec["identity_id"], |
| "finger_id": rec["finger_id"], |
| "sensor_id": rec["sensor_id"], |
| "dataset": rec["dataset"], |
| "image_path": rec["image_path"], |
| } |
|
|
| |
| |
| |
|
|
| def _scan_contact(self, root: Path) -> list[dict[str, str]]: |
| """Scan contact-based_fingerprints/{session}/{X}_{Y}.jpg.""" |
| folder = root / "contact-based_fingerprints" |
| records: list[dict[str, str]] = [] |
| if not folder.exists(): |
| return records |
| for session in self.SESSIONS: |
| session_dir = folder / session |
| if not session_dir.exists(): |
| continue |
| for img_path in sorted(session_dir.iterdir()): |
| if not img_path.is_file(): |
| continue |
| if img_path.suffix.lower() not in IMAGE_EXTS: |
| continue |
| meta = self._parse_contact_filename(img_path) |
| if meta is not None: |
| records.append(meta) |
| return records |
|
|
| def _scan_contactless(self, root: Path) -> list[dict[str, str]]: |
| """Scan processed_contactless_2d_fingerprint_images/{session}/p{X}/p{Y}.bmp.""" |
| folder = root / "processed_contactless_2d_fingerprint_images" |
| records: list[dict[str, str]] = [] |
| if not folder.exists(): |
| return records |
| for session in self.SESSIONS: |
| session_dir = folder / session |
| if not session_dir.exists(): |
| continue |
| |
| for subj_dir in sorted(session_dir.iterdir()): |
| if not subj_dir.is_dir(): |
| continue |
| subj_name = subj_dir.name |
| if not subj_name.lower().startswith("p"): |
| continue |
| try: |
| subject_id = str(int(subj_name[1:])) |
| except ValueError: |
| continue |
| identity_id = f"polyu_{subject_id}" |
| for img_path in sorted(subj_dir.iterdir()): |
| if not img_path.is_file(): |
| continue |
| if img_path.suffix.lower() not in IMAGE_EXTS: |
| continue |
| records.append( |
| { |
| "image_path": str(img_path), |
| "identity_id": identity_id, |
| "finger_id": "f01", |
| "sensor_id": self.SENSOR_CONTACTLESS, |
| "dataset": self.DATASET, |
| } |
| ) |
| return records |
|
|
| @staticmethod |
| def _parse_contact_filename(img_path: Path) -> dict[str, str] | None: |
| """Parse '{X}_{Y}.jpg' → identity_id='polyu_{X}'.""" |
| stem = img_path.stem |
| parts = stem.split("_") |
| if len(parts) != 2: |
| return None |
| try: |
| subject_id = str(int(parts[0])) |
| except ValueError: |
| return None |
| return { |
| "image_path": str(img_path), |
| "identity_id": f"polyu_{subject_id}", |
| "finger_id": "f01", |
| "sensor_id": PolyULoader.SENSOR_CONTACT, |
| "dataset": PolyULoader.DATASET, |
| } |
|
|
