+
+ v1, v2 = hough.lines_from_list([a, b])
+ h1, h2 = hough.lines_from_list([c, d])
+
+ delta_v = ((l1[1][1] - l1[0][1]) * hough.dt) / l1[1][0]
+ delta_h = ((l2[1][1] - l2[0][1]) * hough.dt) / l2[1][0]
+
+ im_l = Image.new('L', size)
+ dr_l = ImageDraw.Draw(im_l)
+ for line in sum(lines, []):
+ dr_l.line(line_from_angl_dist(line, size), width=1, fill=255)
+
+ im_l = im_l.filter(MyGaussianBlur(radius=5))
+ #GaussianBlur is undocumented class, may not work in future versions of PIL
+ im_l_s = im_l.tostring()
+
+ #let's try the bruteforce aproach:
+ k = 30
+
+ pool = multiprocessing.Pool(None)
+
+ tasks = [(im_l_s, v1, v2, h1, h2, x, y, delta_v, delta_h, size) for (x, y) in
+ itertools.product(xrange(-k, k), xrange(-k, k))]
+
+ opt_v = pool.map(job_br1, tasks, 8)
+ opt_h = pool.map(job_br2, tasks, 8)
+ _, x_v, y_v = max(opt_v)
+ _, x_h, y_h = max(opt_h)
+
+ v1 = (v1[0] + x_v * delta_v, v1[1] + x_v)
+ v2 = (v2[0] + y_v * delta_v, v2[1] + y_v)
+ h1 = (h1[0] + x_h * delta_h, h1[1] + x_h)
+ h2 = (h2[0] + y_h * delta_h, h2[1] + y_h)
+
+ grid = get_grid([v1, v2], [h1, h2], size)
+ grid_lines = [[l2ad(l, size) for l in grid[0]],
+ [l2ad(l, size) for l in grid[1]]]
+
+ pool.terminate()
+ pool.join()
+
+### Show error surface
+#
+# from gridf_analyzer import error_surface
+# error_surface(k, im_l_s, v1_i, v2_i, h1_i, h2_i,
+# delta_v, delta_h, x_v, y_v, x_h, y_h, size)
+###
+
+### Show grid over lines
+#
+# im_t = Image.new('RGB', im_l.size, None)
+# im_t_l = im_t.load()
+# im_l_l = im_l.load()
+# for x in xrange(im_t.size[0]):
+# for y in xrange(im_t.size[1]):
+# im_t_l[x, y] = (im_l_l[x, y], 0, 0)
+#
+# im_t_d = ImageDraw.Draw(im_t)
+# for l in grid[0] + grid[1]:
+# im_t_d.line(l, width=1, fill=(0, 255, 0))
+#
+# do_something(im_t, "lines and grid")
+###