我正在尝试使用 Python 和 OpenCV 分割视网膜图像中的血管。这是原始图像:
理想情况下,我希望所有血管都像这样非常明显(不同的图像):
这是我到目前为止所尝试过的。我拍摄了图像的绿色通道。
img = cv2.imread('images/HealthyEyeFundus.jpg')
b,g,r = cv2.split(img)
然后我尝试通过以下方式创建匹配的过滤器本文 http://funcvis.org/blog/?p=51这就是输出图像:
然后我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,显然没有显示所有血管:
我还尝试获取图像的匹配滤波器版本并获取其索贝尔值的大小。
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)
这使得船只更加突出:
然后我尝试了大津阈值处理:
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()
大津没有给出足够的结果。最终结果中包含了噪音:
对于我如何成功分割血管的任何帮助,我们将不胜感激。