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Open Source Computer Vision Library
https://opencv.org/
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108 lines
3.6 KiB
108 lines
3.6 KiB
15 years ago
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#!/usr/bin/python
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from opencv.cv import *
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from opencv.highgui import *
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import sys
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# Rearrange the quadrants of Fourier image so that the origin is at
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# the image center
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# src & dst arrays of equal size & type
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def cvShiftDFT(src_arr, dst_arr ):
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size = cvGetSize(src_arr)
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dst_size = cvGetSize(dst_arr)
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if(dst_size.width != size.width or
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dst_size.height != size.height) :
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cvError( CV_StsUnmatchedSizes, "cvShiftDFT", "Source and Destination arrays must have equal sizes", __FILE__, __LINE__ )
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if(src_arr is dst_arr):
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tmp = cvCreateMat(size.height/2, size.width/2, cvGetElemType(src_arr))
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cx = size.width/2
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cy = size.height/2 # image center
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q1 = cvGetSubRect( src_arr, cvRect(0,0,cx, cy) )
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q2 = cvGetSubRect( src_arr, cvRect(cx,0,cx,cy) )
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q3 = cvGetSubRect( src_arr, cvRect(cx,cy,cx,cy) )
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q4 = cvGetSubRect( src_arr, cvRect(0,cy,cx,cy) )
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d1 = cvGetSubRect( src_arr, cvRect(0,0,cx,cy) )
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d2 = cvGetSubRect( src_arr, cvRect(cx,0,cx,cy) )
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d3 = cvGetSubRect( src_arr, cvRect(cx,cy,cx,cy) )
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d4 = cvGetSubRect( src_arr, cvRect(0,cy,cx,cy) )
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if(src_arr is not dst_arr):
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if( not CV_ARE_TYPES_EQ( q1, d1 )):
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cvError( CV_StsUnmatchedFormats, "cvShiftDFT", "Source and Destination arrays must have the same format", __FILE__, __LINE__ )
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cvCopy(q3, d1)
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cvCopy(q4, d2)
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cvCopy(q1, d3)
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cvCopy(q2, d4)
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else:
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cvCopy(q3, tmp)
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cvCopy(q1, q3)
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cvCopy(tmp, q1)
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cvCopy(q4, tmp)
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cvCopy(q2, q4)
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cvCopy(tmp, q2)
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if __name__ == "__main__":
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im = cvLoadImage( sys.argv[1], CV_LOAD_IMAGE_GRAYSCALE)
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realInput = cvCreateImage( cvGetSize(im), IPL_DEPTH_64F, 1)
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imaginaryInput = cvCreateImage( cvGetSize(im), IPL_DEPTH_64F, 1)
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complexInput = cvCreateImage( cvGetSize(im), IPL_DEPTH_64F, 2)
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cvScale(im, realInput, 1.0, 0.0)
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cvZero(imaginaryInput)
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cvMerge(realInput, imaginaryInput, None, None, complexInput)
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dft_M = cvGetOptimalDFTSize( im.height - 1 )
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dft_N = cvGetOptimalDFTSize( im.width - 1 )
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dft_A = cvCreateMat( dft_M, dft_N, CV_64FC2 )
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image_Re = cvCreateImage( cvSize(dft_N, dft_M), IPL_DEPTH_64F, 1)
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image_Im = cvCreateImage( cvSize(dft_N, dft_M), IPL_DEPTH_64F, 1)
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# copy A to dft_A and pad dft_A with zeros
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tmp = cvGetSubRect( dft_A, cvRect(0,0, im.width, im.height))
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cvCopy( complexInput, tmp, None )
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if(dft_A.width > im.width):
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tmp = cvGetSubRect( dft_A, cvRect(im.width,0, dft_N - im.width, im.height))
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cvZero( tmp )
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# no need to pad bottom part of dft_A with zeros because of
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# use nonzero_rows parameter in cvDFT() call below
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cvDFT( dft_A, dft_A, CV_DXT_FORWARD, complexInput.height )
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cvNamedWindow("win", 0)
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cvNamedWindow("magnitude", 0)
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cvShowImage("win", im)
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# Split Fourier in real and imaginary parts
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cvSplit( dft_A, image_Re, image_Im, None, None )
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# Compute the magnitude of the spectrum Mag = sqrt(Re^2 + Im^2)
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cvPow( image_Re, image_Re, 2.0)
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cvPow( image_Im, image_Im, 2.0)
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cvAdd( image_Re, image_Im, image_Re, None)
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cvPow( image_Re, image_Re, 0.5 )
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# Compute log(1 + Mag)
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cvAddS( image_Re, cvScalarAll(1.0), image_Re, None ) # 1 + Mag
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cvLog( image_Re, image_Re ) # log(1 + Mag)
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# Rearrange the quadrants of Fourier image so that the origin is at
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# the image center
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cvShiftDFT( image_Re, image_Re )
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min, max, pt1, pt2 = cvMinMaxLoc(image_Re)
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cvScale(image_Re, image_Re, 1.0/(max-min), 1.0*(-min)/(max-min))
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cvShowImage("magnitude", image_Re)
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cvWaitKey(0)
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