IDEAL_BANDPASS_CVIP

ideal_bandpass_cvip() - performs ideal bandpass filtering operation.

SYNTAX
DESCRIPTION
REFERENCE
EXAMPLE
CREDITS

SYNTAX

out_s = ideal_bandpass_cvip( spectrum, block_size, transform_type, fc_low, fc_high )

Input Parameters include:

spectrum - An image of size [m n d] which is the spectrum of an image. It can be created by any of the 6 possible transforms availabe in cviptools matlab toolbox: DCT, FFT, Haar, Walsh, Hadamard, Wavelet.

block_size - The same parameter block_size used in the transforms.

transform_type - The user should specify which spectrum is being given to this function. FFT has the origin at the center while the other transforms have their origin located at upper left corner of the image. transform_type is a string. If given spectrum is FFT, then set transform_type = 'fft' or 'center'. Else, the origin would be located at the upper left corner.

fc_low - The low cutoff frequency for band pass filter.

fc_high - The high cutoff frequency for band pass filter.

output parameters include:

out_s - The resultant filtered image.

DESCRIPTION

This function performs 2D bandpass filtering on the spectrum of an image. It applies the ideal bandpass filter of transform type specified by the user to the input spectrum and passes only the frequencies that are within the specified frequency band.

REFERENCE

1.Scott E Umbaugh. DIGITAL IMAGE PROCESSING AND ANALYSIS: Applications with MATLAB and CVIPtools, 3rd Edition.

EXAMPLE

%  Create an spectrum by available transforms

 spectrum = ones(128,256,3);

% Block size

 block_size1  = [];
 block_size2 = [64 128];

% Transform type

 transform_type1 =' fft';
 transform_type2 ='non-fft';
 transform_type3 ='center';

% Low frequency

  fc_low1 = 32;
  fc_low2 = 23;
  fc_low3 = 16;

% High frequency

  fc_high1 = 45;
  fc_high2 = 55;
  fc_high3 = 32;

% Call function

  out_s1 = ideal_bandpass_cvip( spectrum, block_size1,  transform_type1,  fc_low1 ,fc_high1);
  out_s2 = ideal_bandpass_cvip( spectrum,  block_size2, transform_type2,  fc_low2, fc_high2 );
  out_s3 = ideal_bandpass_cvip( spectrum,  block_size2, transform_type3, fc_low3,fc_high3 );

% Display output

  figure; imshow(out_s1,[]);title(' Output with FFT Transform');
  figure; imshow(out_s2,[]);title(' Output with Non FFT Transform')
  figure; imshow(out_s3,[]);title('with center');

CREDITS