Python OpenCV 用滑动条做调色板

# -*- coding: utf-8 -*-

import cv2
import numpy as np


def nothing(x):
    pass

img = np.zeros((300, 512, 3), np.uint8)
cv2.namedWindow('image')

cv2.createTrackbar('R', 'image', 0, 255, nothing)
cv2.createTrackbar('G', 'image', 0, 255, nothing)
cv2.createTrackbar('B', 'image', 0, 255, nothing)

switch = '0:0FF\n1:0N'
cv2.createTrackbar(switch, 'image', 0, 1, nothing)

while True:
    cv2.imshow('image', img)
    k = cv2.waitKey(1) & 0xff
    if k == 27:
        break

    r = cv2.getTrackbarPos('R', 'image')
    g = cv2.getTrackbarPos('G', 'image')
    b = cv2.getTrackbarPos('B', 'image')
    s = cv2.getTrackbarPos(switch, 'image')

    if s == 0:
        img[:] = 0
    else:
        img[:] = [b, g, r]

cv2.destroyAllWindows()

利用调色板的颜色绘制

# -*- coding: utf-8 -*-

import cv2
import numpy as np


#当鼠标按下时变为 True
drawing = False
#如果mode为True绘制矩形， 按下m变成绘制曲线
mode = True
ix, iy = -1, -1

def nothing(x):
    pass

#创建回调函数
def draw(event, x, y, flags, param):
    r = cv2.getTrackbarPos('R', 'image')
    g = cv2.getTrackbarPos('G', 'image')
    b = cv2.getTrackbarPos('B', 'image')
    color = (b, g, r)
    
    global ix, iy, drawing, mode
    #当按下左键时返回起始点坐标
    if event == cv2.EVENT_LBUTTONDOWN:
        drawing = True
        ix, iy = x, y
    #当鼠标按下并移动时绘制图形，可以查看移动，flag是否按下
    elif event == cv2.EVENT_MOUSEMOVE and flags == cv2.EVENT_FLAG_LBUTTON:
        if drawing == True:
            if mode == True:
                cv2.rectangle(img, (ix, iy), (x, y), color, -1)
            else:
                cv2.circle(img, (x, y), 3, color, -1)

    #当鼠标松开时停止绘画
    elif event == cv2.EVENT_LBUTTONUP:
        drawing = False


img = np.zeros((512, 512, 3), np.uint8)
cv2.namedWindow('image')
cv2.createTrackbar('R', 'image', 0, 255, nothing)
cv2.createTrackbar('G', 'image', 0, 255, nothing)
cv2.createTrackbar('B', 'image', 0, 255, nothing)
cv2.setMouseCallback('image', draw)
while True:
    cv2.imshow('image', img)
    k = cv2.waitKey(1) & 0xff
    if k == ord('m'):
        mode = not mode
    elif k == 27:
        break