edgeFeatures             package:EBImage             R Documentation

_E_x_t_r_a_c_t_i_o_n _o_f _e_d_g_e _p_r_o_f_i_l_e_s _a_n_d _e_d_g_e _f_e_a_t_u_r_e_s _f_r_o_m _i_m_a_g_e _o_b_j_e_c_t_s

_D_e_s_c_r_i_p_t_i_o_n:

     Extract the edge profile from image objects, computing for each
     object the distances of edge points to the object geometric
     center, at different rotation angles.

_U_s_a_g_e:

       edgeFeatures(x, ref)
       edgeProfile(x, ref, n=32, fft=TRUE, scale=TRUE, rotate=TRUE)
      

_A_r_g_u_m_e_n_t_s:

       x: An 'Image' object or an array containing object masks. Object
          masks are sets of pixels with the same unique integer value.

     ref: An 'Image' object or an array, containing the intensity
          values of the objects.

       n: An integer value giving the number of angle measures. The
          full circle of '[-pi,pi]' is divided into 'n-1' segments, at
          which edges the profile is approximated. 

     fft: A logical value. If 'TRUE', the resulting profile is the
          'fft' transformation of the distance profile giving the
          frequences of angular changes in shape. 

   scale: A logical value. If 'TRUE', the resulting profile is scaled
          by the effective radius (calcualted as part of
          'link{hull.features}') making the profile scale invariant. 

  rotate: A logical value. If 'TRUE', the resulting profile is shifted
          by the object's roation angle (calculated from the 'moments'
          on the 'ref' image, if provided, and on the hull otherwise. 

_D_e_t_a_i_l_s:

     'edgeFeatures' returns the following features:

        *  'e.irr': difference between the smallest and largest
           distance profile values.

        *  'e.f2Pi': 2pi/1 frequency component of the distance profile.

        *  'e.fPi': 2pi/2 frequency component of the distance profile.

        *  'e.f2Pi3': 2pi/3 frequency component of the distance
           profile.

        *  'e.fPi2': 2pi/4 frequency component of the distance profile.

_V_a_l_u_e:

     'edgeFeatures' returns a matrix (or a list of matrices if 'x'
     contains multiple frames) of features computed of the objects
     present in 'x' and using the intensity values of 'ref'.

     'edgeProfile' returns a matrix ((or a list of matrices if 'x'
     contains multiple frames) of profile values, corresponding, from
     left to right, to the equidistant divisions of the range
     '[-pi,pi]' if 'fft' is 'FALSE'. Otherwise, the matrix contains the
     FFT transform of the corresponding distance profile.

_A_u_t_h_o_r(_s):

     Oleg Sklyar, osklyar@ebi.ac.uk, 2007

_S_e_e _A_l_s_o:

     'getFeatures', 'ocontour'

_E_x_a_m_p_l_e_s:

        example(getFeatures)

