Histograms of Oriented 3D Gradients for Fully Automated Fetal Brain Localization and Robust Motion Correction in 3 T Magnetic Resonance Images

Algorithm 1

Histograms of Oriented 3D Gradients (3DHOG).

Set the block size for image ;

Set the number of histogram bins ;

Set to represent the 3DHOG feature vector;

Compute the image gradient ;

foreach  block  do

  foreach  gradient   in    do

   Transform to spherical coordinates;

   Insert into corresponding histogram bins;

  end

  Normalize block-vector ;

  Append normalized to ;

end