opencv通過滑動條實現漸變相關練習

練習1

描述：寫一個程序，通過調節滑動條來設置閾值threshold1（低閾值）和threshold2（高閾值）進行canny檢測

import cv2 as cv


def nothing(x):
    pass


img = cv.imread("lena.jpg", cv.IMREAD_GRAYSCALE)
cv.namedWindow('image', cv.WINDOW_NORMAL)

# 創建滑動條
cv.createTrackbar('minVal', 'image', 0, 255, nothing)
cv.createTrackbar('maxVal', 'image', 0, 255, nothing)
switch = '0 : OFF\n 1 :ON'
cv.createTrackbar(switch, 'image', 0, 1, nothing)

while 1:
    k = cv.waitKey(1) & 0xFF
    if k == 27:
        break
    minVal = cv.getTrackbarPos('minVal', 'image')
    maxVal = cv.getTrackbarPos('maxVal', 'image')
    s = cv.getTrackbarPos(switch, 'image')

    if s == 0:
        res = img
    else:
        res = cv.Canny(img, minVal, maxVal)
    cv.imshow('image', res)

cv.destroyAllWindows()

效果

練習2

描述：寫一個程序，通過調節滑動條來設置RGB參數顯示

代碼1

# -*- coding:utf-8 -*-
import numpy as np
import cv2 as cv


def nothing(x):
    pass


# 創建一張黑色的圖片，以及一個窗口
img = np.zeros((300, 512, 3), np.uint8)
cv.namedWindow('image', cv.WINDOW_NORMAL)

# 創建滑動條
cv.createTrackbar('R', 'image', 0, 255, nothing)
cv.createTrackbar('G', 'image', 0, 255, nothing)
cv.createTrackbar('B', 'image', 0, 255, nothing)

switch = '0 : OFF\n 1 :ON'
cv.createTrackbar(switch, 'image', 0, 1, nothing)

while 1:
    cv.imshow('image', img)
    k = cv.waitKey(1) & 0xFF
    if k == 27:
        break
    # 獲取四個滑動條的當前位置
    r = cv.getTrackbarPos('R', 'image')
    g = cv.getTrackbarPos('G', 'image')
    b = cv.getTrackbarPos('B', 'image')
    s = cv.getTrackbarPos(switch, 'image')

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

cv.destroyAllWindows()

代碼2

# 通過滾動條模擬調色板效果
# -*- coding:utf-8 -*-
import numpy as np
import cv2 as cv


def to_do(val):  # 定義回調函數
    # 獲取四個滑動條的當前位置
    r = cv.getTrackbarPos('R', 'image')
    g = cv.getTrackbarPos('G', 'image')
    b = cv.getTrackbarPos('B', 'image')
    s = cv.getTrackbarPos(switch, 'image')  # 創建一張黑色的圖片，以及一個窗口
    if s == 0:
        img[:] = 0
    else:
        img[:] = [b, g, r]
    return img


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

# 創建滑動條
cv.createTrackbar('R', 'image', 0, 255, to_do)
cv.createTrackbar('G', 'image', 0, 255, to_do)
cv.createTrackbar('B', 'image', 0, 255, to_do)
switch = '0 : OFF\n 1 :ON'  # 設置圖片顯示的開關
cv.createTrackbar(switch, 'image', 0, 1, to_do)

iimg = to_do(0)

while 1:
    cv.imshow('image', iimg)
    k = cv.waitKey(1000) & 0xFF
    if k == 27:
        break
cv.destroyAllWindows()

效果