Python Pillow image to/from GdkPixbuf with gobject introspection

pixbuf2pillow.py

#!/usr/bin/python3
# vim:fileencoding=utf-8:sw=4:et

# Convert between pygobject Pixbuf and PIL/Pillow image format
# Also a function to do fast gamma correction with Pillow image

from __future__ import print_function, unicode_literals, absolute_import
import sys

from gi.repository import GLib, GdkPixbuf
from PIL import Image

def pixbuf2image(pix):
    """Convert gdkpixbuf to PIL image"""
    data = pix.get_pixels()
    w = pix.props.width
    h = pix.props.height
    stride = pix.props.rowstride
    mode = "RGB"
    if pix.props.has_alpha == True:
        mode = "RGBA"
    im = Image.frombytes(mode, (w, h), data, "raw", mode, stride)
    return im

def image2pixbuf(im):
    """Convert Pillow image to GdkPixbuf"""
    data = im.tobytes()
    w, h = im.size
    data = GLib.Bytes.new(data)
    pix = GdkPixbuf.Pixbuf.new_from_bytes(data, GdkPixbuf.Colorspace.RGB,
            False, 8, w, h, w * 3)
    return pix

def do_gamma(im, gamma):
    """Fast gamma correction with PIL's image.point() method"""
    invert_gamma = 1.0/gamma
    lut = [pow(x/255., invert_gamma) * 255 for x in range(256)]
    lut = lut*3 # need one set of data for each band for RGB
    im = im.point(lut)
    return im

def test_i2p(infile, outfile):
    im = Image.open(infile)
    pix = image2pixbuf(im)
    pix.savev(outfile, "png", (), ())

def test_p2i(infile, outfile):
    pix = GdkPixbuf.Pixbuf.new_from_file(infile)
    im = pixbuf2image(pix)
    # FIXME: We also test gamma correction here
    im = do_gamma(im, 1.8)
    im.save(outfile)

def main():
    infile = sys.argv[1]
    outfile = "pixpil-test.png"
    test_p2i(infile, outfile)
    #test_i2p(infile, outfile)
    print("result saved to {}".format(outfile))

if __name__ == '__main__':
    main()

Hi mozbugbox. There seems to be an issue in GDK such that your image2pixbuf will indirectly result in a memory leak. Christopher Reiter from gitlab.gnome.org/GNOME/pygobject helped me understand the details and suggested this easy workaround, which I thought you probably want to know: replace pixbuf by pixbuf.copy() either inside or outside.

Here is a short script to highlight the problem:

from PIL import Image, ImageColor

import gi
gi.require_version('Gtk', '3.0')
gi.require_version('GdkPixbuf', '2.0')
from gi.repository import Gtk, GdkPixbuf, GLib

from pixbuf2pillow import image2pixbuf

def cb( gtkimage, pilimage ):
	if cb.counter > 60: # run for 1 minute
		return False # discontinue timeout
	cb.counter += 1
	gtkimage.set_from_pixbuf( image2pixbuf( pilimage ) ) # yes leak
	##gtkimage.set_from_pixbuf( image2pixbuf( pilimage ).copy() ) # no leak (can also use .copy inside image2pixbuf)
	return True # continue timeout

topgtkwindow = Gtk.Window( title = "TEST" )
topgtkwindow.connect( "destroy", Gtk.main_quit )

gtkimage = Gtk.Image()
topgtkwindow.add( gtkimage )
topgtkwindow.show_all()

pilimage = Image.new( "RGB", (1200,900), ImageColor.getrgb("Indigo") )

cb.counter = 0
GLib.timeout_add( 1000, cb, gtkimage, pilimage ) # run every 1 second

Gtk.main() # check RAM usage

Best wishes.

[details: https://gitlab.gnome.org/GNOME/pygobject/issues/225]