Question

I’m a beginner in python. All i want to do is create a simple GUI that implements basic Digital Image processing Algorithms.
I want to adjust brightness of an image with tkinter slider. but this is not working and i am clueless as i’m just beginner. I am expecting the scale widget callback to do some brightness adjustment work but due too some reason the call back is not being invoked.

Here is my code:

import Tkinter as tk
import Image
import ImageTk
import numpy as np
import tkFileDialog

class DIP(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent) 
        self.parent = parent        
        self.initUI()

    def initUI(self):
        self.parent.title("DIP Algorithms- Simple Photo Editor")
        self.pack(fill = tk.BOTH, expand = 1)

        menubar = tk.Menu(self.parent)
        self.parent.config(menu = menubar)

        self.label1 = tk.Label(self, border = 25)
        self.label2 = tk.Label(self, border = 25)
        self.label1.grid(row = 1, column = 1)
        self.label2.grid(row = 1, column = 2)

        # File Menu
        fileMenu = tk.Menu(menubar)
        menubar.add_cascade(label = "File", menu = fileMenu)

        # Menu Item for Open Image
        fileMenu.add_command(label = "Open", command = self.onOpen)        

        # Basic menu
        basicMenu = tk.Menu(menubar)        
        menubar.add_cascade(label = "Basic", menu = basicMenu)

        # Menu Item for image negative
        basicMenu.add_command(label = "Negative", command = self.onNeg)

        #menu for brightness
        basicMenu.add_command(label = "Brightness", command = self.onBrghtness)

    def onBrghtness(self):
        #Image Brightness Adjustment Menu callback
        brgTk=tk.Tk()
        self.brgSc = tk.Scale( brgTk, from_=-50, to=50, orient=tk.HORIZONTAL, command=self.adjBright, length=200 ,width=10, sliderlength=15)
        self.brgSc.pack(anchor=tk.CENTER)

    def adjBright(self):
        print self.brgSc #***here how can i get slider value, this callback is not being invoked***???

    def onNeg(self):
        #Image Negative Menu callback
        self.I2 = 255-self.I;
        self.im = Image.fromarray(np.uint8(self.I2))
        photo2 = ImageTk.PhotoImage(self.im)
        self.label2.configure(image=photo2)
        self.label2.image = photo2 # keep a reference!

    def setImage(self):
        self.img = Image.open(self.fn)
        self.I = np.asarray(self.img)
        l, h = self.img.size
        text = str(2*l+100)+"x"+str(h+50)+"+0+0"
        self.parent.geometry(text)
        photo = ImageTk.PhotoImage(self.img)
        self.label1.configure(image = photo)
        self.label1.image = photo # keep a reference!

    def onOpen(self):
        #Open Callback
        ftypes = [('Image Files', '*.tif *.jpg *.png')]
        dlg = tkFileDialog.Open(self, filetypes = ftypes)
        filename = dlg.show()
        self.fn = filename
        #print self.fn #prints filename with path here
        self.setImage()

    #def onError(self):
        #box.showerror("Error", "Could not open file")    


def main():
    root = tk.Tk()
    DIP(root)
    root.geometry("320x240")
    root.mainloop()  

if __name__ == '__main__':
    main()

At the code where i mentioned the problem, the callback is failed because it says something like:

Traceback (most recent call last):
  File "C:\Python27\lib\lib-tk\Tkinter.py", line 1410, in __call__
    return self.func(*args) 
TypeError: adjBright() takes exactly 1 argument (2 given)

Please do help, i know it may be stupid type of question to ask, but i’m just beginner and i hope i’ll have deep understanding of PYTHON with time…

Answer 1

Traceback (most recent call last): File
“C:\Python27\lib\lib-tk\Tkinter.py”, line 1410, in call return
self.func(*args) TypeError: adjBright() takes exactly 1 argument (2
given)

You are getting this error because the scale callback is always passed the new value of the scale. Since you define adjBright to only have self as an argument, Tkinter throws an error. Unfortunately, this seems to be a somewhat under-documented feature of Tkinter.

Add another argument to adjBright, then you don’t have to worry about fetching the new value:

def adjBright(self, new_value):
    print "the slider value is", new_value