Tutorial

Introduction

Image and Data Export

NumCpp provides functions for saving and loading arrays to files. Different file formats are supported. Besides a simple binary export, which serializes the binary data into a file, there is an ascii export, which saves a textual representation to file.

For more advanced file handling there is support for the HDF5 file format, which will require to link against the hdf5 library (-lhdf5):

// create Shepp Logan phantom (type Matrix<double>)
auto x = phantom(256);

// calculate the absolute value of the FFT of x
// the eval call is necessary as abs is an expression template
auto y = eval(abs(fftshift(fft(x))));

// export x and y to an pdf file using different colormaps
export_pdf( x, "shepp_logan_phantom.pdf", colormaps::autumn);
export_pdf( y, "shepp_logan_phantom_fft.pdf");

// export x and y into the same hdf5 file
hdf5write( x, "shepp_logan_phantom.h5", "/shepp_logan" );
hdf5write( y, "shepp_logan_phantom.h5", "/shepp_logan_fft" );

// export x into a simple binary file
tofile( x, "shepp_logan_phantom.dat");