Source code for linef

"""Lines finding module."""

from functools import partial
import sys
from math import sin, cos, pi

try:
    from PIL import Image, ImageDraw
except ImportError, msg:
    print >> sys.stderr, msg
    sys.exit(1)

import filters
from hough import Hough
import ransac

[docs]def prepare(image, show_image, logger): # TODO comment im_l = image.convert('L') show_image(im_l, "ITU-R 601-2 luma transform") logger("edge detection") im_edges = filters.edge_detection(im_l) show_image(im_edges, "edge detection") im_h = filters.high_pass(im_edges, 100) show_image(im_h, "high pass filters") return im_h
[docs]def transform(image, hough, show_image): # TODO comment im_hough = hough.transform(image) show_image(im_hough, "hough transform") # im_hough = filters.peaks(im_hough) # show_image(im_hough, "peak extraction") im_h2 = filters.high_pass(im_hough, 128) show_image(im_h2, "second high pass filters") im_h2 = filters.components(im_h2, 2) show_image(im_h2, "components centers") return im_h2
[docs]def run_ransac(image): # TODO comment # TODO vizualize this image_l = image.load() width, height = image.size data = [] for y in xrange(0, height): for x in xrange(0, width): if image_l[x, y] > 128: data.append((x, y)) if y < 30: data.append((width - x, y + height)) dist = 3 [(line, points), (line2, points2)] = ransac.ransac_multi(2, data, dist, 250) line_to_points = lambda (a, b, c), x: (x, (a*x + c) / (- b)) # TODO width should not be here vvv # TODO refactor gridf to use standard equations instead of points line = [line_to_points(line, 0), line_to_points(line, width - 1)] line2 = [line_to_points(line2, 0), line_to_points(line2, width - 1)] return [sorted(points), sorted(points2)], line, line2
[docs]def find_lines(image, show_image, logger): """Find lines in the *image*.""" logger("preprocessing") show_image(image, "original image") im_h = prepare(image, show_image, logger) hough = Hough.default(im_h) logger("hough transform") im_h2 = transform(im_h, hough, show_image) logger("finding the lines") r_lines, l1, l2 = run_ransac(im_h2) lines = map(hough.lines_from_list, r_lines) # TODO refactor gridf to get rid of this: bounds = sum(map(lambda l: [l[0], l[-1]], r_lines), []) # sum(list, []) = flatten list # TODO do this only if show_all is true: image_g = image.copy() draw = ImageDraw.Draw(image_g) for line in [l for s in lines for l in s]: draw.line(line_from_angl_dist(line, image.size), fill=(120, 255, 120)) show_image(image_g, "lines") return lines, l1, l2, bounds, hough # TODO
[docs]def line_from_angl_dist((angle, distance), size): """Take *angle* and *distance* (from the center of the image) of a line and size of the image. Return the line represented by two points.""" if pi / 4 < angle < 3 * pi / 4: y1 = - size[1] / 2 x1 = int(round((y1 * cos(angle) + distance) / sin(angle))) + size[0] / 2 y2 = size[1] / 2 x2 = int(round((y2 * cos(angle) + distance) / sin(angle))) + size[0] / 2 return [(x1, 0), (x2, size[1])] else: x1 = - size[0] / 2 y1 = int(round((x1 * sin(angle) - distance) / cos(angle))) + size[1] / 2 x2 = size[0] / 2 y2 = int(round((x2 * sin(angle) - distance) / cos(angle))) + size[1] / 2 return [(0, y1), (size[0], y2)]