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%matplotlib notebook
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# loading standard modules
import numpy as np
import matplotlib.pyplot as plt
from skimage import img_as_ubyte
from skimage.color import rgb2grey
# loading custom module (requires file asg1.py in the same directory as the notebook file)
from asg1 import Figure, RegionGrowingPresenter, MaskBuilder
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class MyRegionGrowing:
none_value = 0
threshold_value = 2
def __init__(self, img):
self.fig = Figure()
self.pres = RegionGrowingPresenter(img, self)
self.pres.connect_figure(self.fig)
num_rows = self.num_rows = img.shape[0]
num_cols = self.num_cols = img.shape[1]
# creating gray-scale version of the image
self.intensities = img_as_ubyte(rgb2grey(img))
# mask “region_mask_builder” where pixels of each “region” will have a unique index-label (like 1,2,3,…)
# the default mask value in is “none-value” (0) implying pixels that do not belong to any region (yet)
self.region_mask_builder = MaskBuilder(num_rows, num_cols, self.none_value)
# region counter
self.last_used_region_value = self.none_value
# 4-neighbors graph: pair (neighbor_xs[i],neighbor_xs[j]) defines horizontal and vertical shift to the “i”-th neighbor)
# self.neighbor_xs = [0, 1, 0, -1]
# self.neighbor_ys = [1, 0, -1, 0]
# 8-neighbors graph: pair (neighbor_xs[i],neighbor_xs[j]) defines horizontal and vertical shift to the “i”-th neighbor)
self.neighbor_xs = [0, 1, 1, 1, 0, -1, -1, -1]
self.neighbor_ys = [1, 1, 0, -1, -1, -1, 0, 1]
def run(self):
self.fig.show()
# The function below is called from “on_mouse_down” in RegionGrowingPresenter”.
# It’s goal is to traverse the “region” grown from seed (sx,sy) and mark pixels in this region
# by a unique index-label (new-region-value) in the mask (region_mask_builder)
def grow_new_region_starting_at(self, sx, sy):
num_rows = self.num_rows
num_cols = self.num_cols
neighbor_xs = self.neighbor_xs
neighbor_ys = self.neighbor_ys
num_neighbors = len(neighbor_xs)
I = self.intensities
# obtain “current” region index-label (increments region counter)
new_region_value = self.get_new_region_value()
queue = []
queue.append((sx,sy))
# the loop below implements Breadth-First-Search (BFS)
while len(queue) != 0:
x,y = queue.pop(0)
for k in xrange(num_neighbors):
nx = x + neighbor_xs[k]
ny = y + neighbor_ys[k]
if 0 <= nx and nx < num_cols and 0 <= ny and ny < num_rows: if self.region_mask_builder.get_value_at(nx,ny) == self.none_value and abs(int(I[y,x]) - int(I[ny,nx])) < self.threshold_value: self.region_mask_builder.add_point(nx,ny, new_region_value) queue.append((nx,ny)) # This function increments the region counter (index of the "current" region) def get_new_region_value(self): new_region_value = self.last_used_region_value + 1 self.last_used_region_value = new_region_value return new_region_value def get_region_mask(self): return self.region_mask_builder.get_mask() Notes about the region growing interface:¶ 1. To grow a new region (left) click on a seed inside this region 2. The left click generates "on_mouse_down" event activating the corresponding (call-back) function in "RegionGrowingPresenter" (implemented in asg1.py) contained by "MyRegionGrowing" object. 3. This function first calls "grow_new_region_starting_at" that adds a new region to the mask "region_mask_buiulder" (an array of region indicator labels). 4. Then, the same "on_mouse_down" function calls "get_region_mask" in order to color the image according to this updated mask. In [4]: img = plt.imread('images/uwocampus.bmp') app = MyRegionGrowing(img[:800,:800]) app.run()  In [ ]: