title: Python OpenCV - How to save a 5 channel image
body: <p>I'm using Google Colab with Python 3 and I need to merge 3 images to make a new one with 5 channels, but i get this error:</p>
  
  <p><code>error: OpenCV(4.1.2) /io/opencv/modules/imgcodecs/src/loadsave.cpp:668: error: (-215:Assertion failed) image.channels() == 1 || image.channels() == 3 || image.channels() == 4 in function 'imwrite_'</code></p>
  
  <p>I understand that <code>cv2.imwrite</code> doesn't save a 5 channel image, but how can I do it?</p>
  
  <p>Here is my code:</p>
  
  <pre><code>import numpy as np
  import matplotlib.pyplot as plt
  import cv2
  
  """Read each channel into a numpy array. 
  Of course your data set may not be images yet.
  So just load them into 5 different numpy arrays as neccessary"""
  imgRGB = cv2.imread("/content/drive/My Drive/teste/LC08_L1TP_222063_20180702_20180716_01_T1_1_3.tif")
  b,g,r = cv2.split(imgRGB)
  tir = cv2.imread("/content/drive/My Drive/teste/LC08_L1TP_222063_20180702_20180716_01_T1_TIR_1_3.tif", 0)
  qb = cv2.imread("/content/drive/My Drive/teste/LC08_L1TP_222063_20180702_20180716_01_T1_QB_1_3.tif", 0)
  
  """Create a blank image that has 5 channels 
  and the same number of pixels as your original input"""
  needed_multi_channel_img = np.zeros((b.shape[0], b.shape[1], 5))
  
  """Add the channels to the needed image one by one"""
  needed_multi_channel_img [:,:,0] = b
  needed_multi_channel_img [:,:,1] = g
  needed_multi_channel_img [:,:,2] = r
  needed_multi_channel_img [:,:,3] = tir
  needed_multi_channel_img [:,:,4] = qb
  
  """Save the needed multi channel image"""
  cv2.imwrite("/content/drive/My Drive/teste/Merged_5C.tif",needed_multi_channel_img)
  </code></pre>