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auto-archiver/src/auto_archiver/enrichers/pdq_hash_enricher.py
2023-06-26 17:32:19 +01:00

43 lines
1.5 KiB
Python

import pdqhash
import numpy as np
from PIL import Image
from loguru import logger
from . import Enricher
from ..core import Metadata
class PdqHashEnricher(Enricher):
"""
Calculates perceptual hashes for Media instances using PDQ, allowing for (near-)duplicate detection.
Ideally this enrichment is orchestrated to run after the thumbnail_enricher.
"""
name = "pdq_hash_enricher"
def __init__(self, config: dict) -> None:
# Without this STEP.__init__ is not called
super().__init__(config)
@staticmethod
def configs() -> dict:
return {}
def enrich(self, to_enrich: Metadata) -> None:
url = to_enrich.get_url()
logger.debug(f"calculating perceptual hashes for {url=}")
for m in to_enrich.media:
for media in m.all_inner_media(True):
if media.is_image() and media.get("id") != "screenshot" and len(hd := self.calculate_pdq_hash(media.filename)):
media.set("pdq_hash", hd)
def calculate_pdq_hash(self, filename):
# returns a hexadecimal string with the perceptual hash for the given filename
with Image.open(filename) as img:
# convert the image to RGB
image_rgb = np.array(img.convert("RGB"))
# compute the 256-bit PDQ hash (we do not store the quality score)
hash_array, _ = pdqhash.compute(image_rgb)
hash = "".join(str(b) for b in hash_array)
return hex(int(hash, 2))[2:]