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When image is transformed using 2d fourier transform we can visualize the output as:

enter image description here

I think I understand correctly that those lines that come from the center represent high frequencies in horizontal/vertical direction when the size value of frequency related the to length of the line.

What the those lines that seem to connect the ends of those lines comming from the center mean? How is value of sine/cosine visible on this image?

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The lines connecting the ends seem also parallel to existing lines with a similar pattern but faded a lot more.

I think they are the 2D equivalent of harmonics.

Maybe start with a generated straight line segment at a small angle, e.g. $\pi / 6$ rad. Not end-to-end, and maybe not even centered.

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  • $\begingroup$ Ok would it be right if i say that those are the same line cause of the same angle but the frequency = pixel change is higher for those cause they are in high frequency zone ? $\endgroup$ – Hyphen Jan 15 at 22:17
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    $\begingroup$ No, more like there is a lot of energy in a certain direction, some of it flows away to a harmonic. Harmonics may vary if the signal is non-stationary in 1D. This is the 2D version $\endgroup$ – Pieter21 Jan 16 at 7:17

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