图像

读、写、展示

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img = cv2.imread(img_path)
cv2.imwrite(save_path, img)
cv2.imshow(name_of_window, img)

基础操作

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img.shape	# (rows, columns, channels)
img.size	# (total number of pixels)
img.dtype	# (datatype of image)
img2 = cv2.resize(img, (w,h), interpolation)	# interpolation=cv2.INTER_CUBIC

画矩形框

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import cv2

# color:(*,*,*)
# thickness:粗细(thickness=-1表示填充效果)
cv2.rectangle(img, (x,y), (x+w,y+h), color, thickness=3)

画圆

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# r:半径
cv2.circle(img, (x,y), r, color, thickness)

绘制文字

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# e.g. font = cv2.FONT_HERSHEY_COMPLEX
# thickness=-1表示填满
cv2.putText(img, 'text', (x,y), font, size, color, thickness)

Resize

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cv2.resize(img, (w,h))

PIL.Image 和 OpenCV 图像格式转换

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# PIL 转 OpenCV
img = Image.open('1.jpg')
img = cv2.cvtColor(numpy.asarray(img), cv2.COLOR_RGB2BGR)

# OpenCV 转 PIL
img = cv2.imread('1.jpg')
img = Image.fromarray(cv2.cvtColor(img, cv2.COLOR_BGR2RGB))

视频

写视频

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import cv2

# 定义视频参数
fps = 30
fourcc = cv2.VideoWriter_fourcc(*'DIVX')
writer = cv2.VideoWriter(video_name, fourcc, fps, (w,h))

# 写入视频帧
for ...
	writer.write(img)
...

# 释放
writer.release()