OpenCV基础之画图

OpenCV基础之画图

纯色背景

# 该改代码能够绘制一幅300x300像素的黑色图像
import numpy as np
import matlotlib.pyplot as plt
import cv2

image = np.zeros((300, 300, 3), dtype='uint8') # 创建图像数据，每个像素都为(0,0,0)
plt.imshow(image) # 绘制图像
plt.axis("off") # 关闭坐标轴
plt.show() # 显示图像

直线

'''
@brief Draws a line segment connecting two points.

The function line draws the line segment between pt1 and pt2 points in the image. 
The line is clipped by the image boundaries. For non-antialiased lines with integer coordinates, the 8-connected or 4-connected Bresenham algorithm is used. 
Thick lines are drawn with rounding endings. Antialiased lines are drawn using Gaussian filtering.

@param img Image.
@param pt1 First point of the line segment.
@param pt2 Second point of the line segment.
@param color Line color.
@param thickness Line thickness.
@param lineType Type of the line. See #LineTypes.
@param shift Number of fractional bits in the point coordinates.
'''
cv2.line(img, pt1, pt2, color[, thickness[, lineType[, shift]]]) -> image

# 示例：绘制黑色背景板，并在上面画一条绿色直线
import numpy as np
import matplotlib.pyplot as plt
import cv2

image = np.zeros((300, 300, 3), dtype='uint8') # 创建图像数据，每个像素都为(0,0,0)

green = (0, 255, 0) # 直线颜色：R=0, G=255, B=0 （绿色）
cv2.line(image, (0, 0), (300, 300), green, 5) # 起点(0,0),终点(300,300),绿色,线宽5.

plt.imshow(image) # 绘制图像
plt.axis("off") # 关闭坐标轴
plt.show() # 显示图像

矩形

'''
@brief Draws a simple, thick, or filled up-right rectangle.

The function cv::rectangle draws a rectangle outline or a filled rectangle whose two opposite corners are pt1 and pt2.

@param img Image.
@param pt1 Vertex of the rectangle.
@param pt2 Vertex of the rectangle opposite to pt1 .
@param color Rectangle color or brightness (grayscale image).
@param thickness Thickness of lines that make up the rectangle. Negative values, like #FILLED, mean that the function has to draw a filled rectangle.
@param lineType Type of the line. See #LineTypes
@param shift Number of fractional bits in the point coordinates.
'''
cv2.rectangle(img, pt1, pt2, color[, thickness[, lineType[, shift]]]) -> img

# 示例
# 示例：绘制黑色背景板，在左上角绘制一个空心矩形，在右下角绘制一个实心矩形
import numpy as np
import matplotlib.pyplot as plt
import cv2

image = np.zeros((300, 300, 3), dtype='uint8') # 创建图像数据，每个像素都为(0,0,0)
red = (255, 0, 0)
blue = (0, 0, 255)

cv2.rectangle(image, (50, 50), (100, 100), red, 2) # 矩形左上角（50,50）、右下角（100,100），红色，线宽为2
cv2.rectangle(image, (200, 200), (260, 260), blue, -1) # 矩形左上角（200,200）、右下角（300,300），蓝色，矩形内部全部填充

plt.imshow(image) # 绘制图像
plt.axis("off") # 关闭坐标轴
plt.show() # 显示图像

圆

'''
@brief Draws a circle.

The function cv::circle draws a simple or filled circle with a given center and radius.
@param img Image where the circle is drawn.

@param center Center of the circle.
@param radius Radius of the circle.
@param color Circle color.
@param thickness Thickness of the circle outline, if positive. Negative values, like #FILLED, mean that a filled circle is to be drawn.
@param lineType Type of the circle boundary. See #LineTypes
@param shift Number of fractional bits in the coordinates of the center and in the radius value.
'''
cv2.circle(img, center, radius, color[, thickness[, lineType[, shift]]]) -> img

# 示例：绘制黑色背景板，以（100,100）为圆心绘制一个半径为50的红色空心圆，以(200,200)为圆心绘制一个半径为50的绿色实心圆
import numpy as np
import matplotlib.pyplot as plt
import cv2

image = np.zeros((300, 300, 3), dtype='uint8') # 创建图像数据，每个像素都为(0,0,0)
red = (255, 0, 0)
green = (0, 255, 0)

cv2.circle(image, (100,100), 50, red, 2) # 圆心(100,100)，半径50，红色，线宽为2
cv2.circle(image, (200,200), 50, green, -1) # 圆心(200,200)，半径50，绿色，圆内部填充

plt.imshow(image)
plt.axis("off")
plt.show()