如何使用OpenCV Python创建一个RGB颜色调色板的滑动条？- 技术经验 -卓越飞翔博客

在OpenCV中，可以使用 cv2.reateTrackbar()函数创建轨迹栏。要访问所选轨迹栏位置的值，我们使用 cv2.getTrackbarPos() 函数。

使用这两个函数，我们创建一个包含 R、G、B 颜色的跟踪栏的窗口和一个用于显示所选颜色的颜色窗口。通过改变轨迹条的位置RGB颜色在0和255之间变化。请参阅以下这两个函数的语法。

语法

cv2.createTrackbar(trackbar_name, window_name, default_value, max_value, callback_func)
cv2.getTrackbarPos(trackbar_name, window_name)

参数

trackbar_name - 这是轨迹栏名称。该名称用于访问轨迹栏位置值。
window_name - 这是跟踪栏所附加的窗口的名称。
default_value - 为轨迹栏设置的默认值。
max_value - 轨迹栏的最大值。
callback_func - 当轨迹栏值更改时执行的函数。

步骤

要创建一个RGB调色板的轨迹栏，可以按照下面给出的步骤操作 -

第一步是导入所需的库。所需的 Python 库是 OpenCV 和 NumPy。确保您已经安装了它们。

import cv2
import numpy as np

接下来，定义一个回调函数。它将轨迹栏位置作为默认参数。我们定义这个函数不执行任何操作。

def nothing(x):
   pass

定义黑色图像并创建一个名为Trackbar Color Palette的窗口。轨迹栏和颜色将显示在此窗口中。

img = np.zeros((300,650,3), np.uint8)
window_name = \'Trackbar Color Palette\'
cv2.namedWindow(window_name, cv2.WINDOW_AUTOSIZE)

通过所有五个参数创建用于颜色更改的轨迹栏。轨迹栏值的范围在 0 到 255 之间。

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

获取所有三种 RGB 颜色的当前轨迹栏位置。

r = cv2.getTrackbarPos(\'R\',window_name)
g = cv2.getTrackbarPos(\'G\',window_name)
b = cv2.getTrackbarPos(\'B\',window_name)

更新上述颜色的彩色图像窗口。

img[:] = [b,g,r]

现在在颜色窗口中显示所选轨迹栏值的颜色。

while(True):
   cv2.imshow(window_name,img)
   k = cv2.waitKey(1) & 0xFF
   if k == ord(\'q\'):
      break

示例 1

在下面的Python程序中，我们创建一个窗口作为调色板。我们为 R、G 和 B 颜色创建了三个轨迹栏。滑动滑动条即可在颜色窗口中显示相应的颜色。

# import required libraries</span>
import</span> cv2
import</span> numpy as</span> np

def</span> nothing</span>(</span>x)</span>:</span>
   pass</span>
   
# Create a black image, and the window</span>
img =</span> np.</span>zeros(</span>(</span>300</span>,</span>650</span>,</span>3</span>)</span>,</span> np.</span>uint8)</span>
window_name =</span> \'Trackbar Color Palette\'</span>
cv2.</span>namedWindow(</span>window_name,</span> cv2.</span>WINDOW_AUTOSIZE)</span>

# create trackbars for color change</span>
cv2.</span>createTrackbar(</span>\'R\'</span>,</span>window_name,</span>0</span>,</span>255</span>,</span>nothing)</span>
cv2.</span>createTrackbar(</span>\'G\'</span>,</span>window_name,</span>0</span>,</span>255</span>,</span>nothing)</span>
cv2.</span>createTrackbar(</span>\'B\'</span>,</span>window_name,</span>0</span>,</span>255</span>,</span>nothing)</span>
while</span>(</span>True</span>)</span>:</span>
   cv2.</span>imshow(</span>window_name,</span>img)</span>
   k =</span> cv2.</span>waitKey(</span>1</span>)</span> &</span> 0xFF</span>
   if</span> k ==</span> ord</span>(</span>\'q\'</span>)</span>:</span>
      break</span>
      
   # get current positions of four trackbars</span>
   r =</span> cv2.</span>getTrackbarPos(</span>\'R\'</span>,</span>window_name)</span>
   g =</span> cv2.</span>getTrackbarPos(</span>\'G\'</span>,</span>window_name)</span>
   b =</span> cv2.</span>getTrackbarPos(</span>\'B\'</span>,</span>window_name)</span>
   img[</span>:</span>]</span> =</span> [</span>b,</span>g,</span>r]</span>
 cv2.</span>destroyAllWindows(</span>)</span>

输出

当您运行上述程序时，您将看到以下输出窗口。要关闭输出窗口，请按“q”按钮。

如何使用OpenCV Python创建一个RGB颜色调色板的滑动条？

所有三个轨迹栏的默认值均为零，窗口的颜色为黑色。滑动滑动条即可在颜色窗口中看到相应的颜色。

示例 2

在此程序中，我们创建一个窗口作为带有切换按钮的调色板。

我们创建了四个轨迹栏，三个用于 R、G、B 颜色，一个用于切换按钮。

当开关按钮为ON时，则仅显示颜色窗口中的颜色。滑动滑动条，颜色窗口中就会显示相应的颜色。

import</span> cv2
import</span> numpy as</span> np

def</span> nothing</span>(</span>x)</span>:</span>
   pass</span>
   
# Create a black image, a window</span>
img =</span> np.</span>zeros(</span>(</span>300</span>,</span>650</span>,</span>3</span>)</span>,</span> np.</span>uint8)</span>
window_name =</span> \'Trackbar Color Palette\'</span>
cv2.</span>namedWindow(</span>window_name,</span> cv2.</span>WINDOW_AUTOSIZE)</span>

# create trackbars for color change</span>
cv2.</span>createTrackbar(</span>\'R\'</span>,</span>window_name,</span>0</span>,</span>255</span>,</span>nothing)</span>
cv2.</span>createTrackbar(</span>\'G\'</span>,</span>window_name,</span>0</span>,</span>255</span>,</span>nothing)</span>
cv2.</span>createTrackbar(</span>\'B\'</span>,</span>window_name,</span>0</span>,</span>255</span>,</span>nothing)</span>

# create switch for ON/OFF functionality</span>
# switch = \'0 : OFF \n1 : ON\'</span>
cv2.</span>createTrackbar(</span>"switch"</span>,</span> window_name,</span>0</span>,</span>1</span>,</span>nothing)</span>
while</span>(</span>True</span>)</span>:</span>
   cv2.</span>imshow(</span>window_name,</span>img)</span>
   key =</span> cv2.</span>waitKey(</span>1</span>)</span> &</span> 0xFF</span>
   if</span> key ==</span> ord</span>(</span>\'q\'</span>)</span>:</span>
      break</span>
      
   # get current positions of four trackbars</span>
   r =</span> cv2.</span>getTrackbarPos(</span>\'R\'</span>,</span>window_name)</span>
   g =</span> cv2.</span>getTrackbarPos(</span>\'G\'</span>,</span>window_name)</span>
   b =</span> cv2.</span>getTrackbarPos(</span>\'B\'</span>,</span>window_name)</span>
   s =</span> cv2.</span>getTrackbarPos(</span>"switch"</span>,</span>window_name)</span>
   if</span> s ==</span> 0</span>:</span>
      img[</span>:</span>]</span> =</span> 0</span>
   else</span>:</span>
      img[</span>:</span>]</span> =</span> [</span>b,</span>g,</span>r]</span>
cv2.</span>destroyAllWindows(</span>)</span>

输出

当您运行上面的程序时，它将显示以下输出窗口。要关闭输出窗口，请按“q”按钮。

如何使用OpenCV Python创建一个RGB颜色调色板的滑动条？

所有轨迹栏的默认值为0。窗户的颜色是黑色。当您打开开关（选择1）并将RGB颜色滑块滑动到所需的值时，颜色窗口将显示相应的颜色。

如果在开关关闭（设置为 0）时滑动滑动条，则窗口的颜色不会发生变化。它将保持原样（即黑色）。

语法

参数

步骤

示例 1

输出

示例 2

输出

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