第二部分 - 在Python下使用OpenCV的技巧教程与典型应用案例

# 上下左右，ESC及删除键对应的cv.waitKey()的返回值
# 注意这个值根据操作系统不同有不同，可以通过6.4.2中的代码获取
KEY_UP = 65362
KEY_DOWN = 65364
KEY_LEFT = 65361
KEY_RIGHT = 65363
KEY_ESC = 27
KEY_DELETE = 65535

# 空键用于默认循环
KEY_EMPTY = 0

get_bbox_name = '{}.bbox'.format

# 定义物体框标注工具类
class SimpleBBoxLabeling:

def __init__(self, data_dir, fps=FPS, window_name=None):
self._data_dir = data_dir
self.fps = fps
self.window_name = window_name if window_name else WINDOW_NAME

#pt0是正在画的左上角坐标，pt1是鼠标所在坐标
self._pt0 = None
self._pt1 = None

# 表明当前是否正在画框的状态标记
self._drawing = False

# 当前标注物体的名称
self._cur_label = None

# 当前图像对应的所有已标注框
self._bboxes = []

# 如果有用户自定义的标注信息则读取，否则用默认的物体和颜色
label_path = '{}.labels'.format(self._data_dir)
self.label_colors = DEFAULT_COLOR if not os.path.exists(label_path) else self.load_labels(label_path)

# 获取已经标注的文件列表和还未标注的文件列表
imagefiles = [x for x in os.listdir(self._data_dir) if x[x.rfind('.') + 1:].lower() in SUPPOTED_FORMATS]
labeled = [x for x in imagefiles if os.path.exists(get_bbox_name(x))]
to_be_labeled = [x for x in imagefiles if x not in labeled]

# 每次打开一个文件夹，都自动从还未标注的第一张开始
self._filelist = labeled + to_be_labeled
self._index = len(labeled)
if self._index > len(self._filelist) - 1:
self._index = len(self._filelist) - 1

# 鼠标回调函数
def _mouse_ops(self, event, x, y, flags, param):

# 按下左键时，坐标为左上角，同时表明开始画框，改变drawing标记为True
if event == cv2.EVENT_LBUTTONDOWN:
self._drawing = True
self._pt0 = (x, y)

# 左键抬起，表明当前框画完了，坐标记为右下角，并保存，同时改变drawing标记为False
elif event == cv2.EVENT_LBUTTONUP:
self._drawing = False
self._pt1 = (x, y)
self._bboxes.append((self._cur_label, (self._pt0, self._pt1)))

# 实时更新右下角坐标方便画框
elif event == cv2.EVENT_MOUSEMOVE:
self._pt1 = (x, y)

# 鼠标右键删除最近画好的框
elif event == cv2.EVENT_RBUTTONUP:
if self._bboxes:
self._bboxes.pop()

# 清除所有标注框和当前状态
def _clean_bbox(self):
self._pt0 = None
self._pt1 = None
self._drawing = False
self._bboxes = []

# 画标注框和当前信息的函数
def _draw_bbox(self, img):

# 在图像下方多出BAR_HEIGHT这么多像素的区域用于显示文件名和当前标注物体等信息
h, w = img.shape[:2]
canvas = cv2.copyMakeBorder(img, 0, BAR_HEIGHT, 0, 0, cv2.BORDER_CONSTANT, value=COLOR_GRAY)

# 正在标注的物体信息，如果鼠标左键已经按下，则显示两个点坐标，否则显示当前待标注物体的名称
label_msg = '{}: {}, {}'.format(self._cur_label, self._pt0, self._pt1)
if self._drawing
else 'Current label: {}'.format(self._cur_label)

# 显示当前文件名，文件个数信息
msg = '{}/{}: {} | {}'.format(self._index + 1, len(self._filelist), self._filelist[self._index], label_msg)
cv2.putText(canvas, msg, (1, h+12),
cv2.FONT_HERSHEY_SIMPLEX,
0.5, (0, 0, 0), 1)

# 画出已经标好的框和对应名字
for label, (bpt0, bpt1) in self._bboxes:
label_color = self.label_colors[label] if label in self.label_colors else COLOR_GRAY
cv2.rectangle(canvas, bpt0, bpt1, label_color, thickness=2)
cv2.putText(canvas, label, (bpt0[0]+3, bpt0[1]+15),
cv2.FONT_HERSHEY_SIMPLEX,
0.5, label_color, 2)

# 画正在标注的框和对应名字
if self._drawing:
label_color = self.label_colors[self._cur_label] if self._cur_label in self.label_colors else COLOR_GRAY
if self._pt1[0] >= self._pt0[0] and self._pt1[1] >= self._pt0[1]:
cv2.rectangle(canvas, self._pt0, self._pt1, label_color, thickness=2)
cv2.putText(canvas, self._cur_label, (self._pt0[0] + 3, self._pt0[1] + 15),
cv2.FONT_HERSHEY_SIMPLEX,
0.5, label_color, 2)
return canvas

# 利用repr()导出标注框数据到文件
@staticmethod
def export_bbox(filepath, bboxes):
if bboxes:
with open(filepath, 'w') as f:
for bbox in bboxes:
line = repr(bbox) + ' '
f.write(line)
elif os.path.exists(filepath):
os.remove(filepath)

# 利用eval()读取标注框字符串到数据
@staticmethod
def load_bbox(filepath):
bboxes = []
with open(filepath, 'r') as f:
line = f.readline().rstrip()
while line:
bboxes.append(eval(line))
line = f.readline().rstrip()
return bboxes