繪制矩形¶
概要¶
講解了如何使用OpenCV在圖片中繪制矩形.
keywords OpenCV 矩形繪制
矩形繪制(cv2.rectangle)¶
# 繪制一個邊緣寬度為5的矩形 cv2.rectangle(img=canvas, pt1=(50, 200), pt2=(200, 225), color=COLOR_MAP["green"], thickness=5)
參數說明
-
img圖片(畫布) -
pt1矩形左上角坐標 (x, y) -
pt2矩形右下角坐標 (x, y) -
color顏色 -
thickness邊框寬度 ， 如果是-1代表填充
演示樣例
CH2.3_DrawRectangle.py
import cv2 import numpy as np # 預設幾種顏色 B COLOR_MAP = { "white": (255, 255, 255), "green": (0, 255, 0), "red": (0, 0, 255), "blue" :(255, 0, 0) } ''' 初始化一個彩色的畫布 顏色為BGR色彩空間 ''' def InitCanvas(width, height, color=(255, 255, 255)): canvas = np.ones((height, width, 3), dtype="uint8") canvas[:] = color return canvas canvas = InitCanvas(300, 300, color=COLOR_MAP['white']) # 繪制一個矩形，左上角坐標為(10,10) 矩形右下角坐標為(60,60) cv2.rectangle(canvas, (10, 10), (60, 60), COLOR_MAP['red']) # 繪制一個邊緣為5的矩形 cv2.rectangle(canvas, (50, 200), (200, 225), COLOR_MAP["green"], 5) # 如果寬度(thickness) 設定為-1 則代表填充整個矩形 cv2.rectangle(canvas, (200, 50), (225, 125), COLOR_MAP["blue"], -1) cv2.imshow("Canvas", canvas) cv2.imwrite("draw_rectangle.png", canvas) cv2.waitKey(0)
