Source Code for Module pyvision.edge.sobel

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33   
34  ''' 
35  Created on Oct 18, 2010 
36  @author: Stephen O'Hara 
37  ''' 
38  import cv 
39  import pyvision as pv 
40   
41 -def sobel(im,xorder=1,yorder=0,aperture_size=3,sigma=None): 
42      ''' 
43      void cv.Sobel(src, dst, xorder, yorder, apertureSize = 3)  
44      @param im: Input image 
45      @param xorder: The order of the x derivative (see cv.Sobel openCV docs)  
46      @param yorder: The order of the y derivative (see cv.Sobel openCV docs) 
47      @param aperture_size: How large a convolution window to use 
48      @param sigma: Optional smoothing parameter to be applied prior to detecting edges 
49      ''' 
50      gray = im.asOpenCVBW() 
51      edges = cv.CreateImage(cv.GetSize(gray), 8, 1) 
52       
53      if sigma!=None: 
54          cv.Smooth(gray,gray,cv.CV_GAUSSIAN,int(sigma)*4+1,int(sigma)*4+1,sigma,sigma) 
55   
56      #sobel requires a destination image with larger bit depth...  
57      #...so we have to convert it back to 8 bit for the pv Image... 
58      dst32f = cv.CreateImage(cv.GetSize(gray),cv.IPL_DEPTH_32F,1)  
59       
60      cv.Sobel(gray, dst32f, xorder, yorder, aperture_size) 
61      cv.Convert(dst32f, edges)     
62      edges = pv.Image(edges) 
63           
64      return edges 
65