我正在尝试使用Python和OpenCV分割视网膜图像中的血管。以下是原始图像:
理想情况下,我希望所有的血管都像这张图片一样非常清晰:
目前为止,我尝试了以下方法:我获取了该图像的绿色通道。
这是我得到的结果,很明显没有显示所有的血管:
我还尝试了使用匹配滤波器获取图像并取其sobel值的幅度。
这会使得血管更加突出: 然后我对其进行了大津阈值处理:
Otsu算法无法给出充分的结果。它最终会将噪音包含在结果中:
如果能够成功地将血管分割出来,我将不胜感激。
img = cv2.imread('images/HealthyEyeFundus.jpg')
b,g,r = cv2.split(img)
接下来我按照这篇文章中的方法尝试创建一个匹配滤波器,结果如下图所示:
接着我又尝试进行最大熵阈值处理:
def max_entropy(data):
# calculate CDF (cumulative density function)
cdf = data.astype(np.float).cumsum()
# find histogram's nonzero area
valid_idx = np.nonzero(data)[0]
first_bin = valid_idx[0]
last_bin = valid_idx[-1]
# initialize search for maximum
max_ent, threshold = 0, 0
for it in range(first_bin, last_bin + 1):
# Background (dark)
hist_range = data[:it + 1]
hist_range = hist_range[hist_range != 0] / cdf[it] # normalize within selected range & remove all 0 elements
tot_ent = -np.sum(hist_range * np.log(hist_range)) # background entropy
# Foreground/Object (bright)
hist_range = data[it + 1:]
# normalize within selected range & remove all 0 elements
hist_range = hist_range[hist_range != 0] / (cdf[last_bin] - cdf[it])
tot_ent -= np.sum(hist_range * np.log(hist_range)) # accumulate object entropy
# find max
if tot_ent > max_ent:
max_ent, threshold = tot_ent, it
return threshold
img = skimage.io.imread('image.jpg')
# obtain histogram
hist = np.histogram(img, bins=256, range=(0, 256))[0]
# get threshold
th = max_entropy.max_entropy(hist)
print th
ret,th1 = cv2.threshold(img,th,255,cv2.THRESH_BINARY)
这是我得到的结果,很明显没有显示所有的血管:
![enter image description here](https://istack.dev59.com/5HIoE.webp)
img0 = cv2.imread('image.jpg',0)
sobelx = cv2.Sobel(img0,cv2.CV_64F,1,0,ksize=5) # x
sobely = cv2.Sobel(img0,cv2.CV_64F,0,1,ksize=5) # y
magnitude = np.sqrt(sobelx**2+sobely**2)
这会使得血管更加突出: 然后我对其进行了大津阈值处理:
img0 = cv2.imread('image.jpg',0)
# # Otsu's thresholding
ret2,th2 = cv2.threshold(img0,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)
# Otsu's thresholding after Gaussian filtering
blur = cv2.GaussianBlur(img0,(9,9),5)
ret3,th3 = cv2.threshold(blur,0,255,cv2.THRESH_BINARY+cv2.THRESH_OTSU)
one = Image.fromarray(th2).show()
one = Image.fromarray(th3).show()
Otsu算法无法给出充分的结果。它最终会将噪音包含在结果中:
![enter image description here](https://istack.dev59.com/XkkYd.webp)