function composite_image = InterleaveImages( first_image, second_image, M );

[ row_max, col_max ] = size( first_image );

composite_image = zeros( size( first_image ).*[ 1 2 ] ); 

for col=1:M:col_max
  composite_image(:,2*(col-1)+1:2*(col-1)+M ) = first_image( :, col:col+M-1 );
  composite_image(:,2*(col-1)+M+1:2*(col-1)+2*M ) = fliplr( second_image( :, col:col+M-1 ) );
end