PySide: Separating a spritesheet / Separating an image into contiguous regionsof color

That sounds like something that should be implemented in anything that deals
with sprites, but here we will implement our own sprite-spliter.

The first thing we need here is to extract the individual objects. In this
situation, it is only a matter of deciding whether a pixel is a background one
or not. If we assume the point at origin is a background pixel, then we are
done:

from PIL import Imagedef sprite_mask(img, bg_point=(0, 0)):    width, height = img.size    im = img.load()    bg = im[bg_point]    mask_img = Image.new('L', img.size)    mask = mask_img.load()    for x in xrange(width):        for y in xrange(height): if im[x, y] != bg:     mask[x, y] = 255    return mask_img, bg

If you save the

mask

With the image above, the next thing we need is to fill its holes if we want
to join sprites that are inside others (like the rectangle added, see figure
above). This is another simple rule: if a point cannot be reached from the
point at [0, 0], then it is a hole and it must be filled. All that is left is
then separating each sprite in individual images. This is done by connected
component labeling. For each component we get its axis-aligned bounding box in
order to define the dimensions of the piece, and then we copy from the
original image the points that belong to a given component. To keep it short,
the following pre uses

scipy

import sysimport numpyfrom scipy.ndimage import label, morphologydef split_sprite(img, mask, bg, join_interior=True, basename='sprite_%d.png'):    im = img.load()    m = numpy.array(mask, dtype=numpy.uint8)    if join_interior:        m = morphology.binary_fill_holes(m)    lbl, ncc = label(m, numpy.ones((3, 3)))    for i in xrange(1, ncc + 1):        px, py = numpy.nonzero(lbl == i)        xmin, xmax, ymin, ymax = px.min(), px.max(), py.min(), py.max()        sprite = Image.new(img.mode, (ymax - ymin + 1, xmax - xmin + 1), bg)        sp = sprite.load()        for x, y in zip(px, py): x, y = int(x), int(y) sp[y - int(ymin), x - int(xmin)] = im[y, x]        name = basename % i        sprite.save(name)        print "Wrote %s" % namesprite = Image.open(sys.argv[1])mask, bg = sprite_mask(sprite)split_sprite(sprite, mask, bg)

Now you have all the pieces (sprite_1.png, sprite_2.png, …, sprite_8.png)
exactly as you included in the question.