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iadftview
Generate optical Fourier Spectrum for display from DFT data.

Synopsis

G = iadftview( F )

Implemented in Python.

Input

F Image. Gray-scale (uint8 or uint16) or binary image (logical).

DFT complex data. F(1,1) is the center of the spectrum (u,v)=(0,0)

Output

G Image. Gray-scale uint8 image.

uint8 image suitable for displaying

Description

Generate the logarithm of the magnitude of F, shifted so that the (0,0) stays at the center of the image. This is suitable for displaying only.

Examples

Image and its Fourier Spectrum
>>> import FFT

              
>>> f = iaread('cameraman.pgm')

              

              
>>> iashow(f)

              
(256, 256) Min= 0 Max= 251 Mean=137.066 Std=87.20

              
>>> F = FFT.fft2d(f)

              

              
>>> Fv = iadftview(F)

              

              
>>> iashow(Fv)

              
(256, 256) Min= 50 Max= 255 Mean=128.205 Std=16.56

            

            

              
                

                  
                  
                  
                

                

                  f
                  Fv
                  
                

              
            

          

        

      

    

    

      
Equation

      

        

          

            
          

        

      

    

    

      
Source Code

      

        
def iadftview(F):
    from Numeric import log, ravel, UnsignedInt8
    FM = iafftshift(log(abs(F)+1))
    G = (FM * 255./max(ravel(FM)))
    G = G.astype(UnsignedInt8)
    return G
    

      

    

    

      
See also

      

        

          
            

              iadft
              Discrete Fourier Transform.
            

            

              iaidft
              Inverse Discrete Fourier Transform.
            

            

              iafftshift
              Shifts zero-frequency component to center of spectrum.
            

          
        

      

    

    

      
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