What does phase spectrum of image signal mean?????

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Hello everyone....!!!
I take phase spectrum of an image using Fourier transform, but I don't understand what it represents. So I have some basic doubts:
1.What does phase spectrum of Image actually mean?
2.What information do we get about each pixel from phase spectrum?
3.suppose u are given two phase spectrum instead of actual images,So can u recognize rotation of one image occurred in the second image using phase spectrum only? i have added my code and figure for reference
clc;
clear all;
close all;
i=imread('C:\Users\Public\Pictures\Sample Pictures\index.jpg');
i1=rgb2gray(i);
figure,
subplot(1,2,1);imshow(i1);title('Test image 1');
f1=fftshift(fft2(i1));
phase1=angle(f1);
subplot(1,2,2);imshow(phase1,[]),title('phase spectrum 1');
i2=imrotate(i,45);
i2=rgb2gray(i2);
figure,
subplot(1,2,1);imshow(i2);title('Test image 2');
f2=fftshift(fft2(i2));
phase2=angle(f2);
subplot(1,2,2);imshow(phase2,[]);title('phase spectrum 2');

Accepted Answer

Image Analyst
Image Analyst on 3 Jun 2014
The magnitude of the FFT is like how much energy there is in the sine waves used to build up your image. The phase is like how those sine waves are positioned. For a real, unsymmetrical image, your FFT will be Hermitian. See table about a quarter of the way down this page: http://www.cv.nrao.edu/course/astr534/FourierTransforms.html
  1 Comment
ramdas patil
ramdas patil on 3 Jun 2014
Edited: ramdas patil on 10 Jun 2014
@Image Analyst ,thank u sir but can u comment on my 3rd question given above.??

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More Answers (1)

JB Braendel
JB Braendel on 8 Jun 2014
I'm currently taking a course on continuous time signals, and our prof provided a visual interpretation behind the magnitude and phase spectrum of images:
My confusion however comes from how 2d signal processing works for images. What portion of the image does the FFT represent? Is it an FFT for each row of the image? Each column? An overall mix?
  2 Comments
ramdas patil
ramdas patil on 10 Jun 2014
@JB Braendel A full two-dimensional Fourier transform performs a 1-D transform on every scan-line or row of the image, and another 1-D transform on every column of the image, producing a 2-D Fourier transform of the same size as the original image
ramdas patil
ramdas patil on 10 Jun 2014
@JB Braendel sir, from the figures that u uploaded,....i can come to conclusion that phase part is dominant over magnitude part. can u tell me why is it so.???
also i have reconstructed image (partially) from the phase spectrum alone.but is it possible to reconstruct an image from magnitude spectrum only??

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