Visualize button is not working

[niranjanreddy891]

import tkinter as tk
from tkinter.filedialog import askopenfilename

def browseFile1():
  global infile1
  infile1=askopenfilename()
  txt1.insert(0.0, infile1)

root = tk.Tk()
root.title("Visualization tool")
Label = tk.Label(root, text="Select a PCD file")
Label.grid(row = 1, column = 0, columnspan = 30)
browseButton1 = tk.Button(root,text="Browse", command=browseFile1)
browseButton1.grid(row = 2, column = 30)
txt1 = tk.Text(root, width = 100, height = 1)
txt1.grid(row = 2, column = 0, columnspan = 30)

def processbutton():
  global bro
  bro=processbutton()


browseButton2 = tk.Button(text="Visualize", command = processbutton)
browseButton2.grid(sticky='ew', padx=500, pady=10)


def visualize(cloud):
    global visual
    visual = visualize()
    visual = pcl.pcl_visualization.CloudViewing()

    # filtering ground points
    print(cloud.size)

    fil = cloud.make_passthrough_filter()
    fil.set_filter_field_name("z")
    fil.set_filter_limits(0, 1.5)
    cloud_filtered = fil.filter()

    print(cloud_filtered.size)

###### visualization
    visual.ShowColorCloud(cloud, b'cloud')

    flag = True
    while flag:
        flag != visual.WasStopped()
    end

root.mainloop()

Please help me in this issue. Thanks in advance