X-Git-Url: https://vcs.maemo.org/git/?a=blobdiff_plain;f=samples%2Foctave%2Fdft.m;fp=samples%2Foctave%2Fdft.m;h=69e30b6ad19f56f507e805f77165de5664d5aceb;hb=e4c14cdbdf2fe805e79cd96ded236f57e7b89060;hp=0000000000000000000000000000000000000000;hpb=454138ff8a20f6edb9b65a910101403d8b520643;p=opencv

diff --git a/samples/octave/dft.m b/samples/octave/dft.m
new file mode 100644
index 0000000..69e30b6
--- /dev/null
+++ b/samples/octave/dft.m
@@ -0,0 +1,115 @@
+#! /usr/bin/env octave
+cv;
+highgui;
+
+## Rearrange the quadrants of Fourier image so that the origin is at
+## the image center
+## src & dst arrays of equal size & type
+function cvShiftDFT(src_arr, dst_arr )
+
+  size = cvGetSize(src_arr);
+  dst_size = cvGetSize(dst_arr);
+
+  if(dst_size.width != size.width || \
+     dst_size.height != size.height)
+    cvError( CV_StsUnmatchedSizes, "cvShiftDFT", \
+	    "Source and Destination arrays must have equal sizes", \
+	    __FILE__, __LINE__ );    
+  endif
+
+  if(swig_this(src_arr) == swig_this(dst_arr))
+    tmp = cvCreateMat(size.height/2, size.width/2, cvGetElemType(src_arr));
+  endif
+  
+  cx = size.width/2;
+  cy = size.height/2; # image center
+
+  q1 = cvGetSubRect( src_arr, cvRect(0,0,cx, cy) );
+  q2 = cvGetSubRect( src_arr, cvRect(cx,0,cx,cy) );
+  q3 = cvGetSubRect( src_arr, cvRect(cx,cy,cx,cy) );
+  q4 = cvGetSubRect( src_arr, cvRect(0,cy,cx,cy) );
+  d1 = cvGetSubRect( src_arr, cvRect(0,0,cx,cy) );
+  d2 = cvGetSubRect( src_arr, cvRect(cx,0,cx,cy) );
+  d3 = cvGetSubRect( src_arr, cvRect(cx,cy,cx,cy) );
+  d4 = cvGetSubRect( src_arr, cvRect(0,cy,cx,cy) );
+
+  if(swig_this(src_arr) != swig_this(dst_arr))
+    if( !CV_ARE_TYPES_EQ( q1, d1 ))
+      cvError( CV_StsUnmatchedFormats, \
+	      "cvShiftDFT", "Source and Destination arrays must have the same format", \
+	      __FILE__, __LINE__ );    
+    endif
+    
+    cvCopy(q3, d1);
+    cvCopy(q4, d2);
+    cvCopy(q1, d3);
+    cvCopy(q2, d4);
+    
+  else
+    cvCopy(q3, tmp);
+    cvCopy(q1, q3);
+    cvCopy(tmp, q1);
+    cvCopy(q4, tmp);
+    cvCopy(q2, q4);
+    cvCopy(tmp, q2);
+  endif
+endfunction
+
+
+im = cvLoadImage( argv(){1}, CV_LOAD_IMAGE_GRAYSCALE);
+
+realInput = cvCreateImage( cvGetSize(im), IPL_DEPTH_64F, 1);
+imaginaryInput = cvCreateImage( cvGetSize(im), IPL_DEPTH_64F, 1);
+complexInput = cvCreateImage( cvGetSize(im), IPL_DEPTH_64F, 2);
+
+cvScale(im, realInput, 1.0, 0.0);
+cvZero(imaginaryInput);
+cvMerge(realInput, imaginaryInput, [], [], complexInput);
+
+dft_M = cvGetOptimalDFTSize( im.height - 1 );
+dft_N = cvGetOptimalDFTSize( im.width - 1 );
+
+dft_A = cvCreateMat( dft_M, dft_N, CV_64FC2 );
+image_Re = cvCreateImage( cvSize(dft_N, dft_M), IPL_DEPTH_64F, 1);
+image_Im = cvCreateImage( cvSize(dft_N, dft_M), IPL_DEPTH_64F, 1);
+
+## copy A to dft_A and pad dft_A with zeros
+tmp = cvGetSubRect( dft_A, cvRect(0,0, im.width, im.height));
+cvCopy( complexInput, tmp, [] );
+if(dft_A.width > im.width)
+  tmp = cvGetSubRect( dft_A, cvRect(im.width,0, dft_N - im.width, im.height));
+  cvZero( tmp );
+endif
+
+## no need to pad bottom part of dft_A with zeros because of
+## use nonzero_rows parameter in cvDFT() call below
+
+cvDFT( dft_A, dft_A, CV_DXT_FORWARD, complexInput.height );
+
+cvNamedWindow("win", 0);
+cvNamedWindow("magnitude", 0);
+cvShowImage("win", im);
+
+## Split Fourier in real and imaginary parts
+cvSplit( dft_A, image_Re, image_Im, [], [] );
+
+## Compute the magnitude of the spectrum Mag = sqrt(Re^2 + Im^2)
+cvPow( image_Re, image_Re, 2.0);
+cvPow( image_Im, image_Im, 2.0);
+cvAdd( image_Re, image_Im, image_Re, []);
+cvPow( image_Re, image_Re, 0.5 );
+
+## Compute log(1 + Mag)
+cvAddS( image_Re, cvScalarAll(1.0), image_Re, [] ); # 1 + Mag
+cvLog( image_Re, image_Re ); # log(1 + Mag)
+
+
+## Rearrange the quadrants of Fourier image so that the origin is at
+## the image center
+cvShiftDFT( image_Re, image_Re );
+
+[min, max] = cvMinMaxLoc(image_Re);
+cvScale(image_Re, image_Re, 1.0/(max-min), 1.0*(-min)/(max-min));
+cvShowImage("magnitude", image_Re);
+
+cvWaitKey(-1);