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POdisplaying the ridge orientation as a flow chart
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  1. POdisplaying the ridge orientation as a flow chart
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    copied!<p>I am trying to view my local ridge orientation of a fingerprint as a flowchart. But I seem to fail miserably at doing so. My method consists of the following steps:</p> <ul> <li>use the <code>lro</code> function</li> <li>find the most dominant angle in a 16x16 block</li> <li>create a line segment and rotate it by the dominant angle to display it</li> </ul> <p>The problem is that while the angles that the <code>lro</code> produces are good, the display of these in the flowchart does not work at all. There I just get a lot of random angles going in all kind of directions. Can anyone help me solve this problem?</p> <p>Here is the code I'm using: </p> <pre><code>def lro(im_np): eps = 2**(-52) orientsmoothsigma = 4 # original Gxx = cv2.Sobel(im_np, -1, 2, 0) Gxy = cv2.Sobel(im_np, -1, 1, 1) Gyy = cv2.Sobel(im_np, -1, 0, 2) Gxx = scipy.ndimage.filters.gaussian_filter(Gxx, orientsmoothsigma) Gxy = scipy.ndimage.filters.gaussian_filter(Gxy, orientsmoothsigma) Gyy = scipy.ndimage.filters.gaussian_filter(Gyy, orientsmoothsigma) angle = math.pi/2. + numpy.divide(numpy.arctan2(numpy.multiply(Gxy,2), numpy.subtract(Gxx,Gyy)),2) return angle def createLine(im_np): #Assumes it is 17x17 #Takes in the block-direction #returns a block-direction image as a numpy array angle = numpy.max(im_np) # print im_np.shape im = Image.new('L', (im_np.shape[0], im_np.shape[1]), (0)) draw = ImageDraw.Draw(im) draw.line([(0,im_np.shape[0]/2), (im_np.shape[0],im_np.shape[0]/2)], fill=255) im = im.rotate(angle) img_np2 = numpy.asarray(im) # print img_np2 return img_np2 def findDomAngle(im_np): mask = numpy.zeros((180,2)) for i in range(180): mask[i][0] = i+1 for i in range(im_np.shape[0]): for j in range(im_np.shape[0]): mask[im_np[i][j]-1][1] += 1 max = 0 bestdir = 0 for i in range(180): if mask[i][1] &gt; max: bestdir = i + 1 max = mask[i][1] # print mask # print max return bestdir def blkdir(angle_mat): x = angle_mat.shape[0] y = angle_mat.shape[1] # print angle_mat domAngle = findDomAngle(angle_mat) # print domAngle blkAngle = angle_mat blkAngle.setflags(write=True) for i in range(x): for j in range(y): blkAngle[i][j] = domAngle return blkAngle </code></pre> <p>I am applying another function to process the <code>image</code> block by block, but this method has proven to work so I don't find it relevant to include.</p>
 

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