#!/usr/bin/env python
# vim: set fileencoding=utf-8 :
import math
import numpy
import scipy.ndimage
import bob.core
import bob.io.base
import bob.ip.base
from bob.bio.base.extractor import Extractor
[docs]class RepeatedLineTracking (Extractor):
"""Repeated Line Tracking feature extractor
Based on N. Miura, A. Nagasaka, and T. Miyatake. Feature extraction of finger
vein patterns based on repeated line tracking and its application to personal
identification. Machine Vision and Applications, Vol. 15, Num. 4, pp.
194--203, 2004
"""
def __init__(
self,
iterations = 3000, # Maximum number of iterations
r = 1, # Distance between tracking point and cross section of the profile
profile_w = 21, # Width of profile (Error: profile_w must be odd)
rescale = True,
seed = 0, # Seed for the algorithm's random walk
):
# call base class constructor
Extractor.__init__(
self,
iterations = iterations,
r = r,
profile_w = profile_w,
rescale = rescale,
seed = seed,
)
# block parameters
self.iterations = iterations
self.r = r
self.profile_w = profile_w
self.rescale = rescale
self.seed = seed
[docs] def repeated_line_tracking(self, finger_image, mask):
"""Computes and returns the MiuraMax features for the given input
fingervein image"""
# Sets the random seed before starting to process
numpy.random.seed(self.seed)
finger_mask = numpy.zeros(mask.shape)
finger_mask[mask == True] = 1
# Rescale image if required
if self.rescale == True:
scaling_factor = 0.6
finger_image = bob.ip.base.scale(finger_image,scaling_factor)
finger_mask = bob.ip.base.scale(finger_mask,scaling_factor)
#To eliminate residuals from the scalation of the binary mask
finger_mask = scipy.ndimage.binary_dilation(finger_mask, structure=numpy.ones((1,1))).astype(int)
p_lr = 0.5 # Probability of goin left or right
p_ud = 0.25 # Probability of going up or down
Tr = numpy.zeros(finger_image.shape) # Locus space
filtermask = numpy.array(([-1,-1],[-1,0],[-1,1],[0,-1],[0,0],[0,1],[1,-1],[1,0],[1,1]))
# Check if progile w is even
if (self.profile_w.__mod__(2) == 0):
print ('Error: profile_w must be odd')
ro = numpy.round(self.r*math.sqrt(2)/2) # r for oblique directions
hW = (self.profile_w-1)/2 # half width for horz. and vert. directions
hWo = numpy.round(hW*math.sqrt(2)/2) # half width for oblique directions
# Omit unreachable borders
border = int(self.r+hW)
finger_mask[0:border,:] = 0
finger_mask[finger_mask.shape[0]-border:,:] = 0
finger_mask[:,0:border] = 0
finger_mask[:,finger_mask.shape[1]-border:] = 0
## Uniformly distributed starting points
aux = numpy.argwhere( (finger_mask > 0) == True )
indices = numpy.random.permutation(aux)
indices = indices[0:self.iterations,:] # Limit to number of iterations
## Iterate through all starting points
for it in range(0,self.iterations):
yc = indices[it,0] # Current tracking point, y
xc = indices[it,1] # Current tracking point, x
# Determine the moving-direction attributes
# Going left or right ?
if (numpy.random.random_sample() >= 0.5):
Dlr = -1 # Going left
else:
Dlr = 1 # Going right
# Going up or down ?
if (numpy.random.random_sample() >= 0.5):
Dud = -1 # Going up
else:
Dud = 1 # Going down
# Initialize locus-positition table Tc
Tc = numpy.zeros(finger_image.shape, numpy.bool)
#Dlr = -1; Dud=-1; LET OP
Vl = 1
while (Vl > 0):
# Determine the moving candidate point set Nc
Nr = numpy.zeros([3,3], numpy.bool)
Rnd = numpy.random.random_sample()
#Rnd = 0.8 LET OP
if (Rnd < p_lr):
# Going left or right
Nr[:,1+Dlr] = True
elif (Rnd >= p_lr) and (Rnd < (p_lr + p_ud)):
# Going up or down
Nr[1+Dud,:] = True
else:
# Going any direction
Nr = numpy.ones([3,3], numpy.bool)
Nr[1,1] = False
#tmp = numpy.argwhere( (~Tc[yc-2:yc+1,xc-2:xc+1] & Nr & finger_mask[yc-2:yc+1,xc-2:xc+1].astype(numpy.bool)).T.reshape(-1) == True )
tmp = numpy.argwhere( (~Tc[yc-1:yc+2,xc-1:xc+2] & Nr & finger_mask[yc-1:yc+2,xc-1:xc+2].astype(numpy.bool)).T.reshape(-1) == True )
Nc = numpy.concatenate((xc + filtermask[tmp,0],yc + filtermask[tmp,1]),axis=1)
if (Nc.size==0):
Vl=-1
continue
## Detect dark line direction near current tracking point
Vdepths = numpy.zeros((Nc.shape[0],1)) # Valley depths
for i in range(0,Nc.shape[0]):
## Horizontal or vertical
if (Nc[i,1] == yc):
# Horizontal plane
yp = Nc[i,1]
if (Nc[i,0] > xc):
# Right direction
xp = Nc[i,0] + self.r
else:
# Left direction
xp = Nc[i,0] - self.r
Vdepths[i] = finger_image[int(yp + hW), int(xp)] - 2*finger_image[int(yp),int(xp)] + finger_image[int(yp - hW), int(xp)]
elif (Nc[i,0] == xc):
# Vertical plane
xp = Nc[i,0]
if (Nc[i,1] > yc):
# Down direction
yp = Nc[i,1] + self.r
else:
# Up direction
yp = Nc[i,1] - self.r
Vdepths[i] = finger_image[int(yp), int(xp + hW)] - 2*finger_image[int(yp),int(xp)] + finger_image[int(yp), int(xp - hW)]
## Oblique directions
if ( (Nc[i,0] > xc) and (Nc[i,1] < yc) ) or ( (Nc[i,0] < xc) and (Nc[i,1] > yc) ):
# Diagonal, up /
if (Nc[i,0] > xc and Nc[i,1] < yc):
# Top right
xp = Nc[i,0] + ro
yp = Nc[i,1] - ro
else:
# Bottom left
xp = Nc[i,0] - ro
yp = Nc[i,1] + ro
Vdepths[i] = finger_image[int(yp - hWo), int(xp - hWo)] - 2*finger_image[int(yp),int(xp)] + finger_image[int(yp + hWo), int(xp + hWo)]
else:
# Diagonal, down \
if (Nc[i,0] < xc and Nc[i,1] < yc):
# Top left
xp = Nc[i,0] - ro
yp = Nc[i,1] - ro
else:
# Bottom right
xp = Nc[i,0] + ro
yp = Nc[i,1] + ro
Vdepths[i] = finger_image[int(yp + hWo), int(xp - hWo)] - 2*finger_image[int(yp),int(xp)] + finger_image[int(yp - hWo), int(xp + hWo)]
# End search of candidates
index = numpy.argmax(Vdepths) #Determine best candidate
# Register tracking information
Tc[yc, xc] = True
# Increase value of tracking space
Tr[yc, xc] = Tr[yc, xc] + 1
# Move tracking point
xc = Nc[index, 0]
yc = Nc[index, 1]
img_veins = Tr
# Binarise the vein image
md = numpy.median(img_veins[img_veins>0])
img_veins_bin = img_veins > md
img_veins_bin = scipy.ndimage.binary_closing(img_veins_bin, structure=numpy.ones((2,2))).astype(int)
return img_veins_bin.astype(numpy.float64)
[docs] def skeletonize(self, img):
import scipy.ndimage.morphology as m
h1 = numpy.array([[0, 0, 0],[0, 1, 0],[1, 1, 1]])
m1 = numpy.array([[1, 1, 1],[0, 0, 0],[0, 0, 0]])
h2 = numpy.array([[0, 0, 0],[1, 1, 0],[0, 1, 0]])
m2 = numpy.array([[0, 1, 1],[0, 0, 1],[0, 0, 0]])
hit_list = []
miss_list = []
for k in range(4):
hit_list.append(numpy.rot90(h1, k))
hit_list.append(numpy.rot90(h2, k))
miss_list.append(numpy.rot90(m1, k))
miss_list.append(numpy.rot90(m2, k))
img = img.copy()
while True:
last = img
for hit, miss in zip(hit_list, miss_list):
hm = m.binary_hit_or_miss(img, hit, miss)
img = numpy.logical_and(img, numpy.logical_not(hm))
if numpy.all(img == last):
break
return img
def __call__(self, image):
"""Reads the input image, extract the features based on Maximum Curvature
of the fingervein image, and writes the resulting template"""
finger_image = image[0] #Normalized image with or without histogram equalization
finger_mask = image[1]
return self.repeated_line_tracking(finger_image, finger_mask)