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2 changed files with 30 additions and 15 deletions

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@@ -4,6 +4,7 @@
# All image files # All image files
*.jpg *.jpg
*.jpeg
*.png *.png
*.webp *.webp

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@@ -49,21 +49,29 @@ def _uniform_car_plate(img: cv.typing.MatLike) -> cv.typing.MatLike:
class CarPlateHsvBoundary: class CarPlateHsvBoundary:
lower_bound: cv.typing.MatLike lower_bound: cv.typing.MatLike
upper_bound: cv.typing.MatLike upper_bound: cv.typing.MatLike
need_revert: bool
"""是否取反黑白颜色,因为蓝牌和黄牌的操作正好是反的"""
CAR_PLATE_HSV_BOUNDARIES: tuple[CarPlateHsvBoundary, ...] = ( CAR_PLATE_HSV_BOUNDARIES: tuple[CarPlateHsvBoundary, ...] = (
# 中国蓝牌 HSV 范围 # 中国蓝牌 HSV 范围
CarPlateHsvBoundary(np.array([100, 80, 60]), np.array([130, 255, 255])), CarPlateHsvBoundary(np.array([100, 80, 60]), np.array([130, 255, 255]), True),
# 中国绿牌 HSV 范围 # 中国绿牌 HSV 范围
CarPlateHsvBoundary(np.array([35, 43, 46]), np.array([99, 255, 255])), CarPlateHsvBoundary(np.array([35, 43, 46]), np.array([99, 255, 255]), False),
# 中国黄牌 HSV 范围 # 中国黄牌 HSV 范围
CarPlateHsvBoundary(np.array([32, 43, 46]), np.array([68, 255, 255])), CarPlateHsvBoundary(np.array([16, 43, 46]), np.array([34, 255, 255]), False),
) )
@dataclass
class CarPlateMask:
mask: cv.typing.MatLike
need_revert: bool
"""是否对颜色取反与CarPlateHsvBoundary中的同名字段含义一致"""
def _batchly_mask_car_plate( def _batchly_mask_car_plate(
hsv: cv.typing.MatLike, hsv: cv.typing.MatLike,
) -> typing.Iterator[cv.typing.MatLike]: ) -> typing.Iterator[CarPlateMask]:
""" """ """ """
for boundary in CAR_PLATE_HSV_BOUNDARIES: for boundary in CAR_PLATE_HSV_BOUNDARIES:
# 以给定HSV范围检测符合该颜色的位置 # 以给定HSV范围检测符合该颜色的位置
@@ -76,7 +84,7 @@ def _batchly_mask_car_plate(
mask = cv.morphologyEx(mask, cv.MORPH_OPEN, kernel_open) mask = cv.morphologyEx(mask, cv.MORPH_OPEN, kernel_open)
# Return value # Return value
yield mask yield CarPlateMask(mask, boundary.need_revert)
@dataclass @dataclass
@@ -85,6 +93,8 @@ class CarPlateRegion:
y: int y: int
w: int w: int
h: int h: int
need_revert: bool
"""是否对颜色取反与CarPlateHsvBoundary中的同名字段含义一致"""
MIN_AREA: float = 3000 MIN_AREA: float = 3000
@@ -94,10 +104,10 @@ BEST_ASPECT_RATIO: float = 3.5
def _analyse_car_plate_connection( def _analyse_car_plate_connection(
mask: cv.typing.MatLike, mask: CarPlateMask,
) -> typing.Optional[CarPlateRegion]: ) -> typing.Optional[CarPlateRegion]:
# 连通域分析,筛选最符合车牌长宽比的区域 # 连通域分析,筛选最符合车牌长宽比的区域
num_labels, labels, stats, _ = cv.connectedComponentsWithStats(mask, connectivity=8) num_labels, labels, stats, _ = cv.connectedComponentsWithStats(mask.mask, connectivity=8)
best: typing.Optional[CarPlateRegion] = None best: typing.Optional[CarPlateRegion] = None
best_score = 0 best_score = 0
@@ -113,7 +123,7 @@ def _analyse_car_plate_connection(
score = area * (1 - abs(ratio - BEST_ASPECT_RATIO) / BEST_ASPECT_RATIO) score = area * (1 - abs(ratio - BEST_ASPECT_RATIO) / BEST_ASPECT_RATIO)
if score > best_score: if score > best_score:
best_score = score best_score = score
best = CarPlateRegion(x, y, w, h) best = CarPlateRegion(x, y, w, h, mask.need_revert)
return best return best
@@ -136,10 +146,11 @@ def extract_car_plate(img: cv.typing.MatLike) -> typing.Optional[cv.typing.MatLi
# 连通域分析,筛选最符合车牌长宽比的区域作为车牌 # 连通域分析,筛选最符合车牌长宽比的区域作为车牌
candidate = _analyse_car_plate_connection(mask) candidate = _analyse_car_plate_connection(mask)
# 找到任意一个就退出 # 找到任意一个就退出
if candidate is not None: break if candidate is not None:
break
if candidate is None: if candidate is None:
logging.error('Can not find any car plate.') logging.error("Can not find any car plate.")
return None return None
# 稍微扩边获取最终车牌区域 # 稍微扩边获取最终车牌区域
@@ -149,7 +160,7 @@ def extract_car_plate(img: cv.typing.MatLike) -> typing.Optional[cv.typing.MatLi
y1 = max(candidate.y - pad, 0) y1 = max(candidate.y - pad, 0)
x2 = min(candidate.x + candidate.w + pad, w_img) x2 = min(candidate.x + candidate.w + pad, w_img)
y2 = min(candidate.y + candidate.h + pad, h_img) y2 = min(candidate.y + candidate.h + pad, h_img)
logging.info(f'车牌区域: x={x1}, y={y1}, w={x2 - x1}, h={y2 - y1}') logging.info(f"车牌区域: x={x1}, y={y1}, w={x2 - x1}, h={y2 - y1}")
# # 在原图上标记(仅供调试) # # 在原图上标记(仅供调试)
# debug = img.copy() # debug = img.copy()
@@ -165,17 +176,20 @@ def extract_car_plate(img: cv.typing.MatLike) -> typing.Optional[cv.typing.MatLi
# Otsu 自动阈值,得到白字黑底,再取反 → 黑字白底 # Otsu 自动阈值,得到白字黑底,再取反 → 黑字白底
_, binary_otsu = cv.threshold(blurred, 0, 255, cv.THRESH_BINARY + cv.THRESH_OTSU) _, binary_otsu = cv.threshold(blurred, 0, 255, cv.THRESH_BINARY + cv.THRESH_OTSU)
# 反转:字符变黑,背景变白 # 反转:字符变黑,背景变白
if candidate.need_revert:
binary = cv.bitwise_not(binary_otsu) binary = cv.bitwise_not(binary_otsu)
else:
binary = binary_otsu
# 去除小噪点(开运算) # 去除小噪点(开运算)
kernel_denoise = cv.getStructuringElement(cv.MORPH_RECT, (2, 2)) kernel_denoise = cv.getStructuringElement(cv.MORPH_RECT, (2, 2))
binary = cv.morphologyEx(binary, cv.MORPH_OPEN, kernel_denoise) binary = cv.morphologyEx(binary, cv.MORPH_OPEN, kernel_denoise)
#return binary return binary
# cv.imwrite('./plate_binary.png', binary) # cv.imwrite('./plate_binary.png', binary)
# print("二值化结果已保存: plate_binary.png") # print("二值化结果已保存: plate_binary.png")
# ── 4. 叠加边框轮廓(细化文字边缘,参考效果图)───────────────────── # 叠加边框轮廓(细化文字边缘,参考效果图)
# Canny 边缘叠加让效果更接近参考图 # Canny 边缘叠加让效果更接近参考图
edges = cv.Canny(blurred, 40, 120) edges = cv.Canny(blurred, 40, 120)
edges_inv = cv.bitwise_not(edges) # 边缘→黑色 edges_inv = cv.bitwise_not(edges) # 边缘→黑色