Python中使用Opencv-python库绘制直线、矩形、圆、文本

line()
void cv::line	(	InputOutputArray 	img,
Point 	pt1,
Point 	pt2,
const Scalar & 	color,
int 	thickness = 1,
int 	lineType = LINE_8,
int 	shift = 0 
)		
cv.line(	img, pt1, pt2, color[, thickness[, lineType[, shift]]]	) ->	img

rectangle() [1/2]
void cv::rectangle	(	InputOutputArray 	img,
Point 	pt1,
Point 	pt2,
const Scalar & 	color,
int 	thickness = 1,
int 	lineType = LINE_8,
int 	shift = 0 
)		
Python:
cv.rectangle(	img, pt1, pt2, color[, thickness[, lineType[, shift]]]	) ->	img
cv.rectangle(	img, rec, color[, thickness[, lineType[, shift]]]	) ->	img

rectangle() [2/2]
void cv::rectangle	(	InputOutputArray 	img,
Rect 	rec,
const Scalar & 	color,
int 	thickness = 1,
int 	lineType = LINE_8,
int 	shift = 0 
)		
Python:
cv.rectangle(	img, pt1, pt2, color[, thickness[, lineType[, shift]]]	) ->	img
cv.rectangle(	img, rec, color[, thickness[, lineType[, shift]]]	) ->	img

circle()
void cv::circle	(	InputOutputArray 	img,
Point 	center,
int 	radius,
const Scalar & 	color,
int 	thickness = 1,
int 	lineType = LINE_8,
int 	shift = 0 
)		
Python:
cv.circle(	img, center, radius, color[, thickness[, lineType[, shift]]]	) ->	img

 putText()
void cv::putText	(	InputOutputArray 	img,
const String & 	text,
Point 	org,
int 	fontFace,
double 	fontScale,
Scalar 	color,
int 	thickness = 1,
int 	lineType = LINE_8,
bool 	bottomLeftOrigin = false 
)		
Python:
cv.putText(	img, text, org, fontFace, fontScale, color[, thickness[, lineType[, bottomLeftOrigin]]]	) ->	img

import cv2
import numpy as np

img = np.zeros((512, 512, 3), np.uint8) # 构造高512，宽512, 3通道的Numpy数组
# img = np.zeros((1000, 512, 3), np.uint8)    # 高为1000，宽度为512
# print(img)
print(img.shape)    # （width,height,channels)
# img[:] = 255,0,0    # 将图像img中的所有像素赋值为蓝色（B,G,R）
# img[0:100,200:300] = 0,255,0    # 将高度0-100，宽度200-300的区间像素全部赋值为绿色

cv2.line(img, (0, 0), (img.shape[1], img.shape[0]), (0, 255, 0), 3) # 在图像左上角原点(0,0)到右下角画一条绿色的直线，线条厚度为3
cv2.rectangle(img, (0, 0), (250, 350), (0, 0, 255), 2)  # 在左上角顶点(0,0)和右下角(250,350)处绘制一个红色矩形，边界线条厚度为2
cv2.circle(img, (400, 50), 30, (255, 255, 0), 5)    # 以(400,50)为中心，绘制半径为30的圆，颜色为青色（绿＋蓝＝青（Cyan)）
cv2.putText(img, "OpenCV", (350, 300), cv2.FONT_HERSHEY_COMPLEX, 1, (0, 255, 255), 2)   # 在(350,300)处绘制文字，字体为FONT_HERSHEY_COMPLEX，比例为1，颜色为黄色，厚度为2


cv2.imshow("image", img)    # 绘制图像
cv2.waitKey(0)  # 永久等待用户输入，直到输入按键退出
cv2.destroyAllWindows() # 销毁所有窗口