numpy - How can I make a greyscale copy of a Surface in pygame?

Question

In pygame, I have a surface:

im = pygame.image.load('foo.png').convert_alpha()
im = pygame.transform.scale(im, (64, 64))

How can I get a grayscale copy of the image, or convert the image data to grayscale? I have numpy.

Answer 1

Use a Surfarray, and filter it with numpy or Numeric:

def grayscale(self, img):
    arr = pygame.surfarray.array3d(img)
    #luminosity filter
    avgs = [[(r*0.298 + g*0.587 + b*0.114) for (r,g,b) in col] for col in arr]
    arr = numpy.array([[[avg,avg,avg] for avg in col] for col in avgs])
    return pygame.surfarray.make_surface(arr)