image.cpp

Output

Source

 
#include "sigpack.h"
using namespace arma;
 
int main()
{
    sp::PNM ppm; // Portable Pixel Map
 
    int      R = 120, C = 160;
    mat      x( R, C );
    cx_mat   X( R, C );
    mat      mag( R, C );
    sp::FFTW ss( R, C, FFTW_ESTIMATE );
 
    sp::gplot gp0, gp1;
    gp0.window( "Image", 10, 10, 2 * C + 80, 2 * R + 50 );
    gp1.window( "FFT Blue channel", 640, 10, 2 * C + 80 + 50, 2 * R + 50 );
 
    // Generate test image
    cube x3( R, C, 3, fill::randu );
    x3 *= 100;
    x3.slice( 0 ).submat( span( 20, 51 ), span( 20, 51 ) )   = 250 * ones( 32, 32 ); // Red box
    x3.slice( 1 ).submat( span( 80, 111 ), span( 70, 101 ) ) = 250 * ones( 32, 32 ); // Green box
    x3.slice( 2 ).submat( span( 20, 51 ), span( 110, 141 ) ) = 250 * ones( 32, 32 ); // Blue box
 
    // Write to file
    ppm.write( "test.ppm", ppm.PPM_B, x3, "Test picture" );
 
    // Do FFT of blue channel
    x   = x3.slice( 2 );
    X   = ss.fft2( x );
    mag = 20 * log10( abs( sp::fftshift( X ) ) );
 
    // Plot
    gp0.set_term( "qt" );
    gp0.image( x3 );
    gp1.set_term( "qt" );
    gp1.send2gp( "set palette grey" );
    gp1.image( mag );
 
    return 0;
}