两遍扫描法连通域算法代码python
时间: 2024-05-12 13:12:04 浏览: 16
两遍扫描法是一种图像处理中的连通域算法,它可以用来将一幅图像中的连通区域进行标记和提取。其基本思想是先对图像进行第一遍扫描,给每个像素点赋上一个标记;然后再对图像进行第二遍扫描,将相邻的同种标记的像素合并成一个连通域。
以下是该算法的Python代码:
```
def two_pass_labeling(image):
label = 1
labels = {}
h, w = image.shape[:2]
for y in range(h):
for x in range(w):
if image[y,x] == 0:
continue
neighbors = []
if y > 0:
neighbors.append(labels[(y-1,x)])
if x > 0:
neighbors.append(labels[(y,x-1)])
if not neighbors:
labels[(y,x)] = label
label += 1
else:
neighbor_labels = set(neighbors)
labels[(y,x)] = min(neighbor_labels)
for label in neighbor_labels:
if label != labels[(y,x)]:
relabel(labels, label, labels[(y,x)])
return consolidate_labels(labels)
def relabel(labels, old, new):
for key, value in labels.items():
if value == old:
labels[key] = new
def consolidate_labels(labels):
new_labels = {}
for key, value in labels.items():
new_labels.setdefault(find(labels, value), set()).add(key)
return new_labels
def find(labels, target):
if target not in labels:
return target
path = []
while target != labels[target]:
path.append(target)
target = labels[target]
for point in path:
labels[point] = target
return target
```
其中,第一遍扫描得到每个像素点的标记,第二遍扫描将相邻的同种标记的像素点合并成一个连通域,最终返回一个字典,其中键为连通域的标记,值为连通域的坐标集合。