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#!/usr/bin/python
from opencv.cv import *
from opencv.highgui import *
import sys
# Rearrange the quadrants of Fourier image so that the origin is at
# the image center
# src & dst arrays of equal size & type
def cvShiftDFT(src_arr, dst_arr ):
size = cvGetSize(src_arr)
dst_size = cvGetSize(dst_arr)
if(dst_size.width != size.width or
dst_size.height != size.height) :
cvError( CV_StsUnmatchedSizes, "cvShiftDFT", "Source and Destination arrays must have equal sizes", __FILE__, __LINE__ )
if(src_arr is dst_arr):
tmp = cvCreateMat(size.height/2, size.width/2, cvGetElemType(src_arr))
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(src_arr is not dst_arr):
if( not CV_ARE_TYPES_EQ( q1, d1 )):
cvError( CV_StsUnmatchedFormats, "cvShiftDFT", "Source and Destination arrays must have the same format", __FILE__, __LINE__ )
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)
if __name__ == "__main__":
im = cvLoadImage( sys.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, None, None, 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, None )
if(dft_A.width > im.width):
tmp = cvGetSubRect( dft_A, cvRect(im.width,0, dft_N - im.width, im.height))
cvZero( tmp )
# 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, None, None )
# 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, None)
cvPow( image_Re, image_Re, 0.5 )
# Compute log(1 + Mag)
cvAddS( image_Re, cvScalarAll(1.0), image_Re, None ) # 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, pt1, pt2 = cvMinMaxLoc(image_Re)
cvScale(image_Re, image_Re, 1.0/(max-min), 1.0*(-min)/(max-min))
cvShowImage("magnitude", image_Re)
cvWaitKey(0)
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