Image resize under PhotoImage

Question

I need to resize an image, but I want to avoid PIL, since I cannot make it work under OS X - don\'t ask me why...

Anyway since I am satisfied with gif/pgm/ppm, the P

Answer 1

Because both zoom() and subsample() want integer as parameters, I used both.

I had to resize 320x320 image to 250x250, I ended up with

imgpath = '/path/to/img.png'
img = PhotoImage(file=imgpath)
img = img.zoom(25) #with 250, I ended up running out of memory
img = img.subsample(32) #mechanically, here it is adjusted to 32 instead of 320
panel = Label(root, image = img)

Answer 2

You have to either use the subsample() or the zoom() methods of the PhotoImage class. For the first option you first have to calculate the scale factors, simply explained in the following lines:

scale_w = new_width/old_width
scale_h = new_height/old_height
photoImg.zoom(scale_w, scale_h)

Answer 3

If you don't have PIL installed --> install it

(for Python3+ users --> use 'pip install pillow' in cmd)

from tkinter import *
import tkinter
import tkinter.messagebox
from PIL import Image
from PIL import ImageTk

master = Tk()
 
def callback():
    print("click!")

width = 50
height = 50
img = Image.open("dir.png")
img = img.resize((width,height), Image.ANTIALIAS)
photoImg =  ImageTk.PhotoImage(img)
b = Button(master,image=photoImg, command=callback, width=50)
b.pack()
mainloop()

Answer 4

I just had the same problem, and I found that @Memes' answer works rather well. Just make sure to reduce your ratio as much as possible, as subsample() takes a rather long time to run for some reason.

Basically, the image is zoomed out to the least common factor of the two sizes, and then being subsidized by the origonal size. This leaves you with the image of the desired size.