[Image-SIG] Creating a Transparent Image and Placing it Over Another Image

[Wayne Watson]

BTW, the solution here is:
mask = im.point(lambda i: 255 if i >= 255 else 0)

Wayne Watson wrote:
> Consider this program that I pulled off the web and was posted in 1999.
> It purports to illustrate how one might produce a transparency.
>
>    #!/usr/bin/python
>    # see 
> http://mail.python.org/pipermail/python-list/1999-May/003388.html
>    from Tkinter import *
>    import Image, ImageTk
>    import tkFileDialog
>
>    class Transparency:
>     def __init__(self, parent):
>      self.canvas = Canvas(parent, bg='green')
>      self.canvas.pack()
>      b = Button(parent, command=self.open, text="Select graphics file")
>      b.pack()
>
>     def open(self):
>      self.canvas.delete(ALL)
>      filename = tkFileDialog.askopenfilename()
>      if filename != '':
>       im = Image.open(filename)
>       if im.mode != "RGBA":
>        im = Image.open(filename).convert("RGBA")
>        source = im.split()
>        R, G, B, A = 0, 1, 2, 3
>        mask = im.point(lambda i: i > 0 and 255) # use black as 
> transparent
>        source[A].paste(mask)
>        im = Image.merge(im.mode, source)  # build a new multiband image
>
>       self.graphic = ImageTk.PhotoImage(image=im)
>       self.canvas.create_image(100, 100, image=self.graphic)
>    if __name__ == "__main__":
>     root = Tk()
>     test = Transparency(root)
>     root.mainloop()
>
> It colors the canvas green, and produces a black background. An image is
> merged with the background. I tried out the program. It executes, but I
> do not see where the transparency is apparent. I used a gif with a
> picture of a telescope on a white background, and the result is what I
> would see if I pasted the telescope and white background onto the green
> canvas.
>
> If there's something missing in my observation, I'd like to know what 
> it is.
>

-- 

           Wayne Watson (Watson Adventures, Prop., Nevada City, CA)

             (121.01 Deg. W, 39.26 Deg. N) GMT-8 hr std. time)****

          "Less than all cannot satisfy Man." -- William Blake