[Image-SIG] PIL and multiprocessing module

[Edward Cannon]

You can convert the image to an array and then do whatever you want. Look in the Image documentation. 



On May 13, 2012, at 2:11 PM, John Anderson <sontek at gmail.com> wrote:

> I was wondering if anyone has used PIL with the multiprocessing module.
> 
> I would like to do some pixel by pixel translations using the .load() function and shared memory with the multiprocessing module.
> 
> 
> This is the code I have so far:
> def convert_to_gs_load(surf):
>     width, height = surf.size
>     pix = surf.load()
> 
>     for x in range(width):
>         for y in range(height):
>             alpha = 1
>             red, green, blue = pix[x, y]
>             average = (red + green + blue) // 3
>             gs_color = (average, average, average, alpha)
>             pix[x, y] = gs_color
> 
> def convert_to_gs_load_mp(surf):
>     width, height = surf.size
>     pix = surf.load()
> 
>     t1 = multiprocessing.Process(target=gs_load, args=(pix, width, 0, height / 4))
>     t2 = multiprocessing.Process(target=gs_load, args=(pix, width, height / 4, height / 2))
>     t3 = multiprocessing.Process(target=gs_load, args=(pix, width, height / 2, 3 * height / 4))
>     t4 = multiprocessing.Process(target=gs_load, args=(pix, width, 3 * height / 4, height))
>     threads = [t1, t2, t3, t4]
> 
>     for thread in threads:
>         thread.start()
> 
>     for thread in threads:
>         thread.join()
> 
> The problem is the 'pix' object is not in shared memory, so this doesn't work. Is there a way I could use Value or Array to store the object?
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