code: def show_histogram_window():
      # reset the error label's text
      if lblError["text"] == "Error":
          lblError["text"] = ""
  
      plt.close()
  
      plt.figure()
      plt.title("Colour Histogram")
      plt.xlabel("Bins")
      plt.ylabel("Number of pixels")
  
      colors = ("r", "g", "b")
  
      for i, col in enumerate(colors):
          if not transformedImage is None:
              img = transformedImage
          else:
              img = currentImage
  
          hist = caer.core.cv.calcHist(
              [img], [i], None, [256], [0, 256]
          )
  
          plt.plot(hist, color=col)
          plt.xlim([0, 256])
  
      plt.show()
  
imports: import matplotlib.pyplot
  from matplotlib.backends.backend_tkagg import FigureCanvasTkAgg, NavigationToolbar2Tk
  from matplotlib.figure import Figure
  from tkinter import *
  from tkinter import filedialog
  import platform
  import math
  import caer
label_desc: Use image node_id 14 for calling a global function with example usage: show_histogram_window() without return types