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fast fourier transform frequency limit [closed]

I'm a french student in engineering and I'm given a kind of mandatory technical project to work out on until February. I must investigate the following article : https://www.osapublishing.org/...
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1answer
58 views

Digital frequency for images

From this Wikipedia link, the fastest fequency for digital frequency is 0.5cycle/sample. It can be rewritten as 1cycle/2sample. What does it mean? Does it mean that at least two pixles are required ...
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votes
1answer
1k views

Finding the maximum and minimum frequency of a 2D image

Suppose I transform the image into frequency domain and obtain a 2D array of complex numbers. How can I determine the minimum and maximum frequency from that array? By finding magnitude of each ...
0
votes
2answers
58 views

Retrieve frequency value of an 2D frequency spectrum

How do you retrieve the values of the frequency component occurring in a 2D freq spectrum? I have this, and if I wanted to know the values of the white dots. what should i do ? I apolgize ...
11
votes
2answers
20k views

Image Reconstruction:Phase vs. Magnitude

Figure 1.(c) shows the Test image reconstructed from MAGNITUDE spectrum only. We can say that the intensity values of LOW frequency pixels are comparatively more than HIGH frequency pixels. Figure 1.(...
2
votes
1answer
113 views

Standard representation of FFT of an Image?

Statement 1 : When we take DFT of an image matrix, we get DFT co-efficient matrix. What does the DFT Co-efficients tells about the image? (For example, take the 1st co-eff in the DFT matrix, what ...
5
votes
2answers
284 views

Why we need Frequency and Time information at the same time

The big disadvantage of a DFT is that it has only frequency resolution and no time resolution. This means that although we might be able to determine all the frequencies present in a signal, we do not ...
5
votes
4answers
2k views

Why does the high frequency component of an image contain more noise?

I am working with wavelet transforms. When we apply a discrete wavelet transform to an image, it decomposes into four components named the approximation component, thevertical component, the ...
0
votes
1answer
94 views

Image with specific frequencies

I have created a frequency domain image filter and would like to test it against some images where it is known that the frequencies only occur within a given band. Trouble is, I don't know how to go ...
3
votes
3answers
980 views

Understanding FFT of an Image

I am having trouble identifying the frequency components of an image, Here i simply generated, 256x256 binary-image. ...
3
votes
1answer
446 views

What is the role of Freqency in Digital Images [duplicate]

Possible Duplicate: What does frequency domain denote in case of images? If we look deeply into Digital Images they are purely generated by the pixels distributed in rows and coloumn and the ...