Phase of an image, fft

Can anyone please help me find the phase of this image?This is the fourier transform of another image.

Answer 1

[Image Analyst]

No. You cannot get the phase of a Fourier transform from only the magnitude of the Fourier Transform.

And of course getting the phase of "this" image from the transform of a different "another" image is completely out of the question.

[Arya Gopan]

[Arya Gopan]

Sir I have attached 2 images in the comment section. These are the orginal images that I have. Now I am asked to find the intensity of these images. I dont know how this works but they told me to find the phase of the images, and also told something about taking difference of these. Can you please help me?

[Image Analyst]

The image itself is the intensity of the image.

I stand by my answer that you cannot get the phase of an image from the magnitude of it's spectrum.

That said, you can take the ifft2 of a spatial domain image and get the spectral image which will have real and imaginary parts from which you can get magnitude and phase. Magnitude is the sum of the squares of the real and imaginary parts, and phase (I believe) is the arctangent of the ratio.

[Arya Gopan]

Sir, they have asked me to find the phase by eliminating the background intensity.

i.e by subtracting the images. How is that done?

[Arya Gopan]

Sir my project work is based on measuring the temperature profile of a canle flame. For that I use Mach Zender interferometer and I got 2 images using CCD Camera. one of the burnt candle alone and the other with a background with candle. Now I have to find the phase of the image for which I would crop both the images so as to get a lobule having max intensity. Then I would take the ifft of both the images.Now they have asked me to find the phase by eliminating the background intensity that is by subtracting them. How shall I do it?

[Image Analyst]

You can call imabsdiff with the background image and the flame image. But you cannot use that as your final answer. Why not? Because in the flame itself, it's obscuring the background. The background in the actual flame is not visible and so subtracting it there would not make any sense. So what you can do is to threshold the difference image and create a mask where the difference is less than some value.

mask = imabsdiff(refImage, testImage) < 5; % Or whatever.

Then subtract only within the mask area:

testImage(mask) = testImage(mask) - refImage(mask);

or probably better, just set it to zero there since that's what you're attempting to do anyway.

testImage(mask) = 0;