X-Git-Url: http://vcs.maemo.org/git/?a=blobdiff_plain;f=samples%2Fswig_python%2Fsquares.py;fp=samples%2Fswig_python%2Fsquares.py;h=e953d9b0479863d5d4988d95e8fd5dae8fec847c;hb=e4c14cdbdf2fe805e79cd96ded236f57e7b89060;hp=0000000000000000000000000000000000000000;hpb=454138ff8a20f6edb9b65a910101403d8b520643;p=opencv

diff --git a/samples/swig_python/squares.py b/samples/swig_python/squares.py
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+#!/usr/bin/python
+#
+# The full "Square Detector" program.
+# It loads several images subsequentally and tries to find squares in
+# each image
+#
+
+from opencv.cv import *
+from opencv.highgui import *
+from math import sqrt
+
+thresh = 50;
+img = None;
+img0 = None;
+storage = None;
+wndname = "Square Detection Demo";
+
+def angle( pt1, pt2, pt0 ):
+    dx1 = pt1.x - pt0.x;
+    dy1 = pt1.y - pt0.y;
+    dx2 = pt2.x - pt0.x;
+    dy2 = pt2.y - pt0.y;
+    return (dx1*dx2 + dy1*dy2)/sqrt((dx1*dx1 + dy1*dy1)*(dx2*dx2 + dy2*dy2) + 1e-10);
+
+def findSquares4( img, storage ):
+    N = 11;
+    sz = cvSize( img.width & -2, img.height & -2 );
+    timg = cvCloneImage( img ); # make a copy of input image
+    gray = cvCreateImage( sz, 8, 1 );
+    pyr = cvCreateImage( cvSize(sz.width/2, sz.height/2), 8, 3 );
+    # create empty sequence that will contain points -
+    # 4 points per square (the square's vertices)
+    squares = cvCreateSeq( 0, sizeof_CvSeq, sizeof_CvPoint, storage );
+    squares = CvSeq_CvPoint.cast( squares )
+
+    # select the maximum ROI in the image
+    # with the width and height divisible by 2
+    subimage = cvGetSubRect( timg, cvRect( 0, 0, sz.width, sz.height ))
+
+    # down-scale and upscale the image to filter out the noise
+    cvPyrDown( subimage, pyr, 7 );
+    cvPyrUp( pyr, subimage, 7 );
+    tgray = cvCreateImage( sz, 8, 1 );
+    # find squares in every color plane of the image
+    for c in range(3):
+        # extract the c-th color plane
+        channels = [None, None, None]
+        channels[c] = tgray
+        cvSplit( subimage, channels[0], channels[1], channels[2], None ) 
+        for l in range(N):
+            # hack: use Canny instead of zero threshold level.
+            # Canny helps to catch squares with gradient shading
+            if( l == 0 ):
+                # apply Canny. Take the upper threshold from slider
+                # and set the lower to 0 (which forces edges merging)
+                cvCanny( tgray, gray, 0, thresh, 5 );
+                # dilate canny output to remove potential
+                # holes between edge segments
+                cvDilate( gray, gray, None, 1 );
+            else:
+                # apply threshold if l!=0:
+                #     tgray(x,y) = gray(x,y) < (l+1)*255/N ? 255 : 0
+                cvThreshold( tgray, gray, (l+1)*255/N, 255, CV_THRESH_BINARY );
+
+            # find contours and store them all as a list
+            count, contours = cvFindContours( gray, storage, sizeof_CvContour,
+                CV_RETR_LIST, CV_CHAIN_APPROX_SIMPLE, cvPoint(0,0) );
+
+            if not contours:
+                continue
+            
+            # test each contour
+            for contour in contours.hrange():
+                # approximate contour with accuracy proportional
+                # to the contour perimeter
+                result = cvApproxPoly( contour, sizeof_CvContour, storage,
+                    CV_POLY_APPROX_DP, cvContourPerimeter(contours)*0.02, 0 );
+                # square contours should have 4 vertices after approximation
+                # relatively large area (to filter out noisy contours)
+                # and be convex.
+                # Note: absolute value of an area is used because
+                # area may be positive or negative - in accordance with the
+                # contour orientation
+                if( result.total == 4 and 
+                    abs(cvContourArea(result)) > 1000 and 
+                    cvCheckContourConvexity(result) ):
+                    s = 0;
+                    for i in range(5):
+                        # find minimum angle between joint
+                        # edges (maximum of cosine)
+                        if( i >= 2 ):
+                            t = abs(angle( result[i], result[i-2], result[i-1]))
+                            if s<t:
+                                s=t
+                    # if cosines of all angles are small
+                    # (all angles are ~90 degree) then write quandrange
+                    # vertices to resultant sequence
+                    if( s < 0.3 ):
+                        for i in range(4):
+                            squares.append( result[i] )
+
+    return squares;
+
+# the function draws all the squares in the image
+def drawSquares( img, squares ):
+    cpy = cvCloneImage( img );
+    # read 4 sequence elements at a time (all vertices of a square)
+    i=0
+    while i<squares.total:
+        pt = []
+        # read 4 vertices
+        pt.append( squares[i] )
+        pt.append( squares[i+1] )
+        pt.append( squares[i+2] )
+        pt.append( squares[i+3] )
+
+        # draw the square as a closed polyline
+        cvPolyLine( cpy, [pt], 1, CV_RGB(0,255,0), 3, CV_AA, 0 );
+        i+=4
+
+    # show the resultant image
+    cvShowImage( wndname, cpy );
+
+def on_trackbar( a ):
+    if( img ):
+        drawSquares( img, findSquares4( img, storage ) );
+
+names =  ["../c/pic1.png", "../c/pic2.png", "../c/pic3.png",
+          "../c/pic4.png", "../c/pic5.png", "../c/pic6.png" ];
+
+if __name__ == "__main__":
+    # create memory storage that will contain all the dynamic data
+    storage = cvCreateMemStorage(0);
+    for name in names:
+        img0 = cvLoadImage( name, 1 );
+        if not img0:
+            print "Couldn't load %s" % name
+            continue;
+        img = cvCloneImage( img0 );
+        # create window and a trackbar (slider) with parent "image" and set callback
+        # (the slider regulates upper threshold, passed to Canny edge detector)
+        cvNamedWindow( wndname, 1 );
+        cvCreateTrackbar( "canny thresh", wndname, thresh, 1000, on_trackbar );
+        # force the image processing
+        on_trackbar(0);
+        # wait for key.
+        # Also the function cvWaitKey takes care of event processing
+        c = cvWaitKey(0);
+        # clear memory storage - reset free space position
+        cvClearMemStorage( storage );
+        if( c == '\x1b' ):
+            break;
+    cvDestroyWindow( wndname );