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| from PIL import Image
import matplotlib.pyplot as plt
import numpy as np
import canny
import math
def to_gray(img):
height, width, _ = img.shape
gray = np.zeros((height, width), dtype=np.uint8)
k = np.array([0.299, 0.587, 0.114])
for i in range(height):
for j in range(width):
gray[i][j] = (k * img[i][j]).sum()
return gray
def to_rgb(img):
height, width = img.shape
rgb = np.zeros((height, width, 3), dtype=np.uint8)
for i in range(height):
for j in range(width):
rgb[i][j] = [img[i][j]] * 3
return rgb
def plot_line(img, expression):
if len(img.shape) != 3 or img.shape[2] != 3:
print('The image shape must be (height, width, 3)')
return img
height = img.shape[0]
width = img.shape[1]
def func(x, a, b):
return int(a * x + b)
for exp in expression:
a, b = exp
point = [(x, func(x, a, b)) for x in range(width)
if 0 <= func(x, a, b) < height]
for x, y in point:
img[y][x] = [255, 0, 0]
return img
def hough_check(img, precision=360, threshold=50, number=-1):
height, width = img.shape
theta = range(0, precision)
factor = 360 / precision
tab_height = len(theta)
tab_width = (height + width) << 1
tab = [[0] * tab_width for i in range(tab_height)]
for i in range(height):
for j in range(width):
if img[i][j] == 255:
for k in theta:
arc = k * factor * math.pi / 180
rho = int(j * math.cos(arc) + i * math.sin(arc))
tab[k][rho + height + width] += 1
line = []
for i in range(tab_height):
for j in range(tab_width):
if tab[i][j] > threshold:
line.append((i * factor, j - height - width))
if number == -1 or len(line) <= number:
return line
else:
line.sort(key=lambda x: tab[int(x[0] / factor)][x[1] + height + width])
return line[0:number]
def get_expression(pair):
theta, rho = pair
theta = theta * math.pi / 180
k = -math.cos(theta) / (math.sin(theta) + 1e-8)
b = rho / (math.sin(theta) + 1e-8)
return k, b
def hough_with_canny():
filename = 'hf.jpg'
rgb_img = Image.open(filename)
gray_img = rgb_img.convert('L')
gray_array = np.array(gray_img)
gray_array = canny.canny(gray_array, (3, 3))
line = hough_check(gray_array, number=5)
print('The number of lines is {}'.format(len(line)))
expression = [get_expression(x) for x in line]
rgb_array = to_rgb(gray_array)
rgb_array = plot_line(rgb_array, expression)
plt.figure()
plt.imshow(rgb_array)
plt.show()
def hough_without_canny():
filename = 'gray.jpg'
rgb_img = Image.open(filename)
gray_img = rgb_img.convert('L')
gray_array = np.array(gray_img)
rgb_array = to_rgb(gray_array)
line = hough_check(gray_array, number=5)
print('The number of lines is {}'.format(len(line)))
expression = [get_expression(x) for x in line]
rgb_array = plot_line(rgb_array, expression)
plt.figure()
plt.imshow(rgb_array)
plt.show()
if __name__ == '__main__':
hough_without_canny()
|
