def search_by_image(image_content: bytes) -> List[Tuple[float, model.Post]]:
query_signature = image_hash.generate_signature(image_content)
query_words = image_hash.generate_words(query_signature)
"""
The unnest function is used here to expand one row containing the 'words'
array into multiple rows each containing a singular word.
Documentation of the unnest function can be found here:
https://www.postgresql.org/docs/9.2/functions-array.html
"""
dbquery = """
SELECT s.post_id, s.signature, count(a.query) AS score
FROM post_signature AS s, unnest(s.words, :q) AS a(word, query)
WHERE a.word = a.query
GROUP BY s.post_id
ORDER BY score DESC LIMIT 100;
"""
candidates = db.session.execute(dbquery, {"q": query_words})
data = tuple(
zip(*[(post_id, image_hash.unpack_signature(packedsig))
for post_id, packedsig, score in candidates]))
if data:
candidate_post_ids, sigarray = data
distances = image_hash.normalized_distance(sigarray, query_signature)
return [(distance, try_get_post_by_id(candidate_post_id))
for candidate_post_id, distance in zip(candidate_post_ids,
distances)
if distance < image_hash.DISTANCE_CUTOFF]
else:
return []
def test_signature_functions(read_asset, config_injector):
sig1 = image_hash.generate_signature(read_asset('jpeg.jpg'))
sig2 = image_hash.generate_signature(read_asset('jpeg-similar.jpg'))
sig1_repacked = image_hash.unpack_signature(
image_hash.pack_signature(sig1))
sig2_repacked = image_hash.unpack_signature(
image_hash.pack_signature(sig2))
assert array_equal(sig1, sig1_repacked)
assert array_equal(sig2, sig2_repacked)
dist1 = image_hash.normalized_distance([sig1], sig2)
assert abs(dist1[0] - 0.20599895341812172) < 1e-8
dist2 = image_hash.normalized_distance([sig2], sig2)
assert abs(dist2[0]) < 1e-8
words1 = image_hash.generate_words(sig1)
words2 = image_hash.generate_words(sig2)
words_match = sum(word1 == word2 for word1, word2 in zip(words1, words2))
assert words_match == 17
def test_signature_avif(read_asset, config_injector):
sig1 = image_hash.generate_signature(read_asset("avif.avif"))
sig2 = image_hash.generate_signature(read_asset("avif-similar.avif"))
sig1_repacked = image_hash.unpack_signature(
image_hash.pack_signature(sig1))
sig2_repacked = image_hash.unpack_signature(
image_hash.pack_signature(sig2))
assert array_equal(sig1, sig1_repacked)
assert array_equal(sig2, sig2_repacked)
dist1 = image_hash.normalized_distance([sig1], sig2)
assert abs(dist1[0] - 0.22628712858355998) < 1e-8
dist2 = image_hash.normalized_distance([sig2], sig2)
assert abs(dist2[0]) < 1e-8
words1 = image_hash.generate_words(sig1)
words2 = image_hash.generate_words(sig2)
words_match = sum(word1 == word2 for word1, word2 in zip(words1, words2))
assert words_match == 12