Python + OpenCV颜色分割使用Kmeans
问题描述:
我想从opencv应用kmeans为了在HSV色彩空间中分割图像。Python + OpenCV颜色分割使用Kmeans
def leftOffset(src, p_countours):
height, width, size = src.shape
p_width = width/p_countours
o_left = src[0:height, 0:p_width]
HSV_img = cv2.cvtColor(o_left, cv2.COLOR_BGR2HSV)
hue = HSV_img[0]
hue = np.float32(HSV_img)
# Define criteria = (type, max_iter = 10 , epsilon = 1.0)
criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 10, 1.0)
# Set flags (Just to avoid line break in the code)
flags = cv2.KMEANS_RANDOM_CENTERS
# Apply KMeans
compactness,labels,centers = cv2.kmeans(hue,2,criteria,10,flags)
centers = np.uint8(centers)
res = centers[labels.flatten()]
res2 = res.reshape((hue.shape))
cv2.imshow("o_left", hue)
cv2.waitKey(0)
我现在能够在k均值算法应用于HSVImage [0] K = 2,我怎么能得到这样的阈值的图像根据结果呢?
感谢
要澄清一个问题: 我有基于颜色的验证码,我想每一个细分的数字。
我将使用K-means法,找出主色和段内的数字。
答
我可以提出一个传统的替代方案吗?我首先摆脱了非常黑暗和明亮的区域,您可能仅仅依靠从直方图计算出的色调分量的最频繁值。
请注意,数字的边界永远不会绝对精确,因为周围的颜色是相似的。
此外,您可以选择仅限于最大斑点(根据大小)以抑制外部剩余的小斑点。
结果:
代码:
import cv2
import numpy as np
from matplotlib import pyplot as plt
img = cv2.imread('image1.jpg')
#get rid of very bright and very dark regions
delta=30
lower_gray = np.array([delta, delta,delta])
upper_gray = np.array([255-delta,255-delta,255-delta])
# Threshold the image to get only selected
mask = cv2.inRange(img, lower_gray, upper_gray)
# Bitwise-AND mask and original image
res = cv2.bitwise_and(img,img, mask= mask)
#Convert to HSV space
HSV_img = cv2.cvtColor(res, cv2.COLOR_BGR2HSV)
hue = HSV_img[:, :, 0]
#select maximum value of H component from histogram
hist = cv2.calcHist([hue],[0],None,[256],[0,256])
hist= hist[1:, :] #suppress black value
elem = np.argmax(hist)
print np.max(hist), np.argmax(hist)
tolerance=10
lower_gray = np.array([elem-tolerance, 0,0])
upper_gray = np.array([elem+tolerance,255,255])
# Threshold the image to get only selected
mask = cv2.inRange(HSV_img, lower_gray, upper_gray)
# Bitwise-AND mask and original image
res2 = cv2.bitwise_and(img,img, mask= mask)
titles = ['Original Image', 'Selected Gray Values', 'Hue', 'Result']
images = [img, res, hue, res2]
for i in xrange(4):
plt.subplot(2,2,i+1),plt.imshow(images[i],'gray')
plt.title(titles[i])
plt.xticks([]),plt.yticks([])
plt.show()
答
1)如果你只需要找到主色,为什么不找到每个颜色通道的直方图?找到主导通道,然后使用otsu分段该通道?例如,如果我仅限于色相,我可以得到很好的结果。 K-手段可能是承担这一任务的矫枉过正:
import cv2
import numpy as np
import matplotlib.pylab as plt
## Simple Otsu over hue
six = cv2.imread('7zovC.jpg')
##convert to hsv
hsv = cv2.cvtColor(six, cv2.COLOR_BGR2HSV)
hue = hsv[:, :, 0]
binary_img = cv2.threshold(hue, 128, 255, cv2.THRESH_OTSU)
plt.figure()
plt.imshow(binary_img*255)
plt.show()
2)为什么不使用所有渠道集群,而不是仅仅色相?你需要的是聚类 - >颜色量化这个link应该是有用的。这是OpenCV的版本>为Python 3.0.0 2.4.11
注意,cv2.kmeans有轻微差别接口,你可以用这个来代替:
def color_quantize(img, K):
Z = img.reshape((-1, 3))
# convert to np.float32
Z = np.float32(Z)
# define criteria, number of clusters(K) and apply kmeans()
criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 10, 1.0)
ret, label, center = cv2.kmeans(Z, 2, criteria, 10, cv2.KMEANS_RANDOM_CENTERS)
# Now convert back into uint8, and make original image
center = np.uint8(center)
res = center[label.flatten()]
quantized_img = res.reshape((img.shape))
label_img = label.reshape((img.shape[:2]))
return label_img, quantized_img
six = cv2.imread('7zovC.jpg')
##convert to hsv
hsv = cv2.cvtColor(six, cv2.COLOR_BGR2HSV)
K = 2
label_img, six_q = color_quantize(hsv, K)
plt.figure()
plt.imshow(label_img)
plt.show()
我对颜色量化结果并不令人印象深刻。
我不能完全理解这个问题。你能否通过加入图像来澄清? – tfv
@tfv我已添加2个测试图像 – Mix
您使用的是什么版本的opencv? –