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Code Issues Projects Releases Wiki Activity

LPR improvements (#14641)

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This commit is contained in:
Josh Hawkins 2024-10-28 11:49:12 -05:00 committed by Nicolas Mowen
parent 978bc4828c
commit 57e1f30a9e
2 changed files with 29 additions and 5 deletions
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19
frigate/embeddings/alpr/alpr.py
View File

@ -13,6 +13,8 @@ from frigate.embeddings.embeddings import Embeddings
logger = logging.getLogger(__name__)
MIN_PLATE_LENGTH = 3
class LicensePlateRecognition:
def __init__(
@ -197,7 +199,22 @@ class LicensePlateRecognition:
average_confidences[original_idx] = average_confidence
areas[original_idx] = area
return license_plates, average_confidences, areas
# Filter out plates that have a length of less than 3 characters
# Sort by area, then by plate length, then by confidence all desc
sorted_data = sorted(
[
(plate, conf, area)
for plate, conf, area in zip(
license_plates, average_confidences, areas
)
if len(plate) >= MIN_PLATE_LENGTH
],
key=lambda x: (x[2], len(x[0]), x[1]),
reverse=True,
)
if sorted_data:
return map(list, zip(*sorted_data))
return [], [], []

15
frigate/embeddings/maintainer.py
View File

@ -598,7 +598,11 @@ class EmbeddingMaintainer(threading.Thread):
logger.debug("No text detected")
return
top_plate, top_char_confidences = license_plates[0], confidences[0]
top_plate, top_char_confidences, top_area = (
license_plates[0],
confidences[0],
areas[0],
)
avg_confidence = (
(sum(top_char_confidences) / len(top_char_confidences))
if top_char_confidences
@ -609,6 +613,7 @@ class EmbeddingMaintainer(threading.Thread):
if id in self.detected_license_plates:
prev_plate = self.detected_license_plates[id]["plate"]
prev_char_confidences = self.detected_license_plates[id]["char_confidences"]
prev_area = self.detected_license_plates[id]["area"]
prev_avg_confidence = (
(sum(prev_char_confidences) / len(prev_char_confidences))
if prev_char_confidences
@ -618,6 +623,7 @@ class EmbeddingMaintainer(threading.Thread):
# Define conditions for keeping the previous plate
shorter_than_previous = len(top_plate) < len(prev_plate)
lower_avg_confidence = avg_confidence <= prev_avg_confidence
smaller_area = top_area < prev_area
# Compare character-by-character confidence where possible
min_length = min(len(top_plate), len(prev_plate))
@ -628,13 +634,13 @@ class EmbeddingMaintainer(threading.Thread):
)
worse_char_confidences = char_confidence_comparison >= min_length / 2
if shorter_than_previous or (
if (shorter_than_previous or smaller_area) and (
lower_avg_confidence and worse_char_confidences
):
logger.debug(
f"Keeping previous plate. New plate stats: "
f"length={len(top_plate)}, avg_conf={avg_confidence:.2f} "
f"vs Previous: length={len(prev_plate)}, avg_conf={prev_avg_confidence:.2f}"
f"length={len(top_plate)}, avg_conf={avg_confidence:.2f}, area={top_area} "
f"vs Previous: length={len(prev_plate)}, avg_conf={prev_avg_confidence:.2f}, area={prev_area}"
)
return
@ -667,6 +673,7 @@ class EmbeddingMaintainer(threading.Thread):
self.detected_license_plates[id] = {
"plate": top_plate,
"char_confidences": top_char_confidences,
"area": top_area,
}
def _create_thumbnail(self, yuv_frame, box, height=500) -> Optional[bytes]: